'i get it' it means you get something immediatly i got it it means you already get that thing or you have that.

I think as you state the question, you are interested in the common idiom "I get it" -- meaning "I understand". It can be in reference to learning something: "He studied the problem for 20 minutes, then suddenly shouted "Oh, I get it!'" Or sometimes referring to whether or not you see the humor in a joke: "I heard that joke on TV, but I just don't get it. Why is it funny?" "Look at this cartoon in the newspaper. Do you get it?" ... ... "Yes, I get it, but I don't think it's funny." -- or -- ... "Yes, I got it, but I don't think it's funny." Of course, "get" and "got" are also used in the sense of "retrieving" or "obtaining" something: "Can you get some beer on your way home?" ... "Yeah, I can get it." "Whenever my girlfriend catches cold, 3 days later I get it." "Do you have the wedding ring??!!" ... "Don't worry! I got it ! I got it !"

It's the same verb 'get'. So there is no difference. 'Get it' (or 'get something') is used to mean 'to receive the meaning of a joke; to understand something': 'John told a joke, but I didn’t get it.' 'Bob laughed very hard, but Mary didn’t get it.' 'I don’t get you.' 'I don’t get it—why would she do a thing like that?' The same expression can be used to mean 'to receive punishment' (= to catch it): 'John got it for arriving late at school.' 'If your dead finds out, you'll really get it(or 'you'll really get a scolding').

i think learner spotted it already there's no difference on it. cowboy...