invite和invitation的词性不同、含义不同、用法不同。invite表示“邀请”，通常为及物动词，有时不以人宾语，而以事作宾语。常见搭配为invite sb to do sth，意思是邀请某人做某事。Invitation是名词，意思为“邀请、请帖”等。

Why did you invite them here?

你为什么邀请他们到这儿来?

If you invite him, he'll be only too glad to attend.

如果你请他，他一定非常乐意参加。

They invited us to play the game.

他们邀请我们来玩这个游戏。

I should invite them to join us.

我应邀请他们加入我们。

She received a letter of invitation yesterday.

昨天她收到了一封邀请信。