Big Rob, I assume you have Photo Plus, it was one I used years ago and has been improved over the years and does a edit well. Restated: Photo plus has been around for a loooong time, is a "nice" program... but Affinity is a "Great" program and has been built with modern code from foundation up first for MAC and then Windows.

The comparison of the two programs is too complicated for a concise answer.... so if you really want to know, then down load trials of both and take a look for your self the difference will be evident. The above explanation should tell you a lot of Affinity history. Again try Affinity and you will be amazed at the power you have.

If you have Photo Plus and it does what you want and you are comfortable with it, then enjoy it.... many of us tend to buy Corvette cars to drive two blocks to the 7-11 when the VW accomplishes that task just fine. If Photo Plus meets your demands.. as with most things in life it is perhaps better to KIS... Keep it simple...

http://affinity.serif.com/en-gb/

Affinity imaging software is a completely new program,
which was only available to MAC users.
Now, this new program is available to both MAC and Windows users.
Lightroom 6 is, in the main a file management program with some
manipulation tools.
One of the many differences, too many to list here, is Lightroom 6 does not
have Layers, were as Affinity does.
I have read quite a few favourable reviews of this new program.

Its market place position is not against Lightroom 6 or Photoshop CC,
but against Photoshop Elements and other photographic programs which
offer manipulation of images, the price does reflect this.

Serif has been making affordable rivals to professional graphics tools like Photoshop, QuarkXPress and Illustrator for decades, but in 2015 it did something unexpected.
Rather than converting its PhotoPlus, PagePlus and DrawPlus programs to the Apple Mac, it launched a completely new series called Affinity.

It was an instant hit with Apple uses, and now Serif is bringing it to the PC to replace its existing range.
So while Affinity Photo has been around for 18 months, it's only now available to Windows users and if you already have PhotoPlus, this will be your next upgrade.

Developing a completely new set of programs from scratch is a brave move and it's paid off.
The breadth of features you got for your money in Serif's Plus software, but it was all about imitating professional packages at a lower cost rather than offering a different way of working. Affinity rethinks the whole approach to each task based on what regular users actually want to do and it turns out that tools that suit pros better are probably easier for the rest of us to get to grips with too.
For example, it's particularly noticeable that you can try everything on the am image you're looking at, not via a small preview. You can even roll back your command history (multiple undo) visually, watching the image change back as you drag a slider and for many operations you can also drag across the image to compare before and after.

Inevitably, the breadth and depth of features' can't quite match Photoshop, whose ever-increasing toolbox sprawls out into areas like 3D modelling, but for everyday image retouching and composition, even at a serious level, there's not much you will miss. Selection tools, healing brushes and content aware fill let chop and change images seamlessly and full layer support means you can try all kinds of advanced techniques.

Filter layers let you add advanced effects to all or sections of an image that are reversible, so you can still edit everything later. Raw pictures from higher-quality digital cameras can be imported and tweaked for maximum control over exposure and tone and a full range of export options is available.

One issue, while Affinity runs smoothly on even quite modest Macs, thanks to programming that makes use of Apples' optimisation technologies, it struggle a bit on a Windows 10 laptop, longer than Photoshop for similar commands to complete.

DirectX 11 and Direct 2D acceleration is supported, so if you have a decent graphics card you should fare better.
Unlike Photoshop, you don't have to buy Affinity Photo on subscription and at under £50 ($62.40 current exchange rate) - less than half Adobe's annual fee - it's a great deal.

Affinity is not to be compared with Lightroom. It is to be compared with Photoshop. Affinity is a full-featured replacement for PS. Affinity does not organize images like LR. I have never used LR, but organized with Bridge. Now I mostly use FastStone Viewer for organizing and Affinity for all manipulation. I've toyed with the idea of using LightZone, but haven't done so.

There are many tutorials on Youtube for Affinity. If you have used PS, Affinity is fairly easy to learn. I'm not sure there are any books on Affinity, but I've used the Youtube to learn it.

Serif has been making affordable rivals to professional graphics tools like Photoshop, QuarkXPress and Illustrator for decades, but in 2015 it did something unexpected.
Rather than converting its PhotoPlus, PagePlus and DrawPlus programs to the Apple Mac, it launched a completely new series called Affinity.

It was an instant hit with Apple uses, and now Serif is bringing it to the PC to replace its existing range.
So while Affinity Photo has been around for 18 months, it's only now available to Windows users and if you already have PhotoPlus, this will be your next upgrade.

Developing a completely new set of programs from scratch is a brave move and it's paid off.
The breadth of features you got for your money in Serif's Plus software, but it was all about imitating professional packages at a lower cost rather than offering a different way of working. Affinity rethinks the whole approach to each task based on what regular users actually want to do and it turns out that tools that suit pros better are probably easier for the rest of us to get to grips with too.
For example, it's particularly noticeable that you can try everything on the am image you're looking at, not via a small preview. You can even roll back your command history (multiple undo) visually, watching the image change back as you drag a slider and for many operations you can also drag across the image to compare before and after.

Inevitably, the breadth and depth of features' can't quite match Photoshop, whose ever-increasing toolbox sprawls out into areas like 3D modelling, but for everyday image retouching and composition, even at a serious level, there's not much you will miss. Selection tools, healing brushes and content aware fill let chop and change images seamlessly and full layer support means you can try all kinds of advanced techniques.

Filter layers let you add advanced effects to all or sections of an image that are reversible, so you can still edit everything later. Raw pictures from higher-quality digital cameras can be imported and tweaked for maximum control over exposure and tone and a full range of export options is available.

One issue, while Affinity runs smoothly on even quite modest Macs, thanks to programming that makes use of Apples' optimisation technologies, it struggle a bit on a Windows 10 laptop, longer than Photoshop for similar commands to complete.

DirectX 11 and Direct 2D acceleration is supported, so if you have a decent graphics card you should fare better.
Unlike Photoshop, you don't have to buy Affinity Photo on subscription and at under £50 ($62.40 current exchange rate) - less than half Adobe's annual fee - it's a great deal.