The only problem with tubes is light loss. There are no optics in the tubes so you still get a perfect sharp image but they can cost you dearly in light particularly as your extension increases.

If you have noise it's the camera (probably ISO) not the tubes.

In terms of a macro lens, I have a 60 mm and a 105 mm both Nikon FX lenses. The sixty is used rarely, the working distance is too short for anything living. I use that one mostly to photograph copy, and stationary subjects. The 105 is something else. It was my favourite for a number of years. It has image stabilization that makes it easier to do hand held stuff. And it's a reasonable weight and is razor sharp.

However I also have two Sigma macro lenses, a 150 mm and a 180 mm. Both of these have image stabilizers too and both are equal to the Nikon lenses I own. I got the 180 mm lens initially to increase my reach (working distance) but to my dismay the front element is too large so I can't attach my ring flash or my Nikon macro flash. That then prompted me to also get the 150 mm. When I need flash, which isn't very often in fact, I use the 150. The rest of the time the 180 does an admirable job. I also have a 200 mm macro from Nikon. As macro len ses go it's ok and sharp but it doesn't have an image stabilizer and it's an f4 lens to boot. I used it for a while but found my two Sigma macros do a lot better images.

In terms of DOF, there isn't any as you increase your magnifications. I usually close my aperture all the way down (f32, f40 etc) and that can get me some reasonable depth of field at the cost of light of course. I also use focus stacking sometimes. But one neat trick which saves the day is to not do head on shots. When I do a long insect like a grasshopper I shoot it from the side. That way the entire insect is sharp instead of only the head.

Returning to your original question, yes there is a difference between tubes and a macro lens. The macro lens is designed to focus on a flat plane compared to normal lenses which focus on a curved plane. So you get a different image from a macro lens compared to a normal one. The tubes only magnify, that is, they let you get closer. They do not change the curvature or flatness of the field of the lens.

Because of this I always work with macro lenses for little stuff, and I will sometimes boost my magnification by attaching tubes or a bellows or both to the macro lens. I will not attach them to a normal lens. But then that's me. When I was young and more poor I used to do all kinds of combinations some of which worked surprisingly well. That then taught me what gets me the best images. So do experiment.

The images below are a couple of rain drop images and a small bug. All three were done with a macro lens.