A big difference! :) I guess you mean only verbs (actions).
We add -s only for he/she/it: She works every day. ("I works" is not correct) Present simple tense for habits and general facts.
We add "to be" and -ing for continuous or temporary actions. I was working on that. They are working slowly today. He is working as a waiter for the moment. (Again, "I working" is not correct).
I hope that helps a little.