Is Maaser and giving Tzedakah two different things? If I give a Chomesh, is it better I give only 10% and then be able to give more Tzedakah?

Tzedaka and Maaser are different, although interconnected:

Tzedaka – is to give to poor people; essentially it has no limit (although that depends on various factors), and every time they ask you are obligated to give. Tzedaka is a Mitzvah Min Hatorah.

Maaser – may be given towards other Mitzvos as well; it is a set amount, and there is a Machlokes whether it is Min Hatorah, Mederabanan, or a Minhag which was accepted and obligates us (due to general Minhag, ancestors Minhag or it is like a Neder). Chomesh is a Mitzvah Min Hamuvchar, an enhancement of the Mitzvah, but not obligatory on any level.

If you have already been giving Chomesh, and when you started you had in mind to always do so, or you have done so at least three times, you should not stop (unless there is financial trouble, which is a different question).

I’m not sure what other Tzedaka you were referring to, but you may use Chomesh itself to give to those Tzedakos.