I think it is basically just the level of relaxing that you do to the hair. Texlaxing is one step down from relaxer, and texturizer one step down from texlaxing.
So it really just depends on the amount of curl you want to keep in your hair and then finding the right combination of product and application that gets you those results. I do think that your natural curl pattern sometimes plays a part in the choice. I get what could be considered "texlaxed" - I use Designer Touch texturizing relaxer, which leaves some of my curl pattern but still gets my hair straight with roller sets. I have parts of my hair in the front that have very little curl pattern and more of a "z" pattern. I have parts in the middle and back that have a very strong curl "s" pattern. When I get a relaxer, I get a looser curl/wave pattern in the middle and back, but the front can tend to just be frizzy. In other words, my front areas are better off all natural or bone straight. I find the in between is not ideal for that part of my hair. But since my hair is fine, I prefer using a milder relaxer, which is why I switched from Affirm.
So I would say base it on how fine your hair is, the curl pattern you want to acheive and pick your products and methods from there.