you compare girls and boys and see which one you like better
Is girls a main verb?
No girls is a plural noun.
Try putting the word in a sentence to see if it is a verb. For
example you can say -- She hit me. So try making the same sentence
with girls -- She girls me. Hopefully you can see that this is not
a correct sentence.
Do boys see opptical illusions faster or slower than girls?
yes. they happen to find and see things better than girls!