Spanish language Q&A Forum

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In Kwiziq, there's a lesson on -ito etc and a lesson on -illo etc. I'm living in Ecuador and have traveled around Central and South America a bit, and I've heard both groups of suffixes used in what seems to be the exact same way. I guess I'm looking for a little clarity on whether they are 100% interchangeable. 

Am I correct that team -ito and team -illo mean the same thing - they make a word diminutive, softer, affectionate - and that the real difference is just in local usage? I can use either group of suffixes, and not be wrong, but one group is just more common in certain areas than the other?

My apologies if you've answered this elsewhere. I reviewed the other questions, and I did not find an answer that makes me confident that my understanding is correct.

And thanks, in advance for your help.

The lesson is clear that "bueno" in front of a noun means "great," but simply "good" if after the noun.  So the instruction is that this girl simply wants a good man.  But the "correct" choice is "un buen hombre"!

In the example given:
"¿Tienes algún problema? No, pero gracias por preguntar."

Why is it not "algúnas" to match the gender of problema?