Make (something) up, makeup, make up with, make up to, make out, make out with. These are all totall

Make (something) up = to lie, to create a story that isn't real or true.

e.g.

A: Yesterday, I met David Beckham and he told me I was more handsome than he is.

B: Really? Did he really say that or are you making it up?

A: Yeah, just kidding. I made it up.

makeup = beauty products that people put on their faces.

Makeup is not a verb, it is a noun. You can not say "I am makeup" "I will makeup"

e.g.

A: I need to do my makeup before I go to work.

B: You don't need to wear makeup, you're beautiful already!

make up with (somebody) = when you make friends with somebody again after you have an argument or fight.

e.g.

A: I had a big arguement with my brother last week. But we made up with eachother yesterday.

B: What did you fall out about? (fall out = argue / fight)

A: He said he couldn't pay back the money he owes me.

Make (something) up to (somebody) = do something good/nice to say sorry for something bad you did in the past.

e.g.

A: I forgot my friend's birthday so I took her to a posh restaurant to make it up to her. (posh = hi-so)

B: Was she okay after that?

A: Kind of, I also bought her a new bag and then she wasn't mad at me anymore.

Make out / Make out with = kissing another person

A: I made out with Paul last week, I hope my boyfriend doesn't find out! (find out = learn / know)

B: Why did you do that?

A: He's just so handsome.