Correct spelling, explanation: different comes from the verb differ to which suffix -ent is added. The suffix -ent is used often to create adjectives out of verbs, like in the case of suffice → sufficient. This is why different form of the word.

Definition of different:
Adjective
1. Not similar to something or to each other; not the same as something
We don’t argue much even though we have very different opinions.

Idioms with different:
1. (to be) different sides of the same coin – to differ in some aspects, while still having something in common.
I hate him, but I have to admit, we’re different sides of the same coin. Sometimes it scares me, how many things we can agree on!
2. different as night and day
Maybe there is some truth to saying that opposites attract; Lucy and her husband are different as night and day but they seem happy together.

Incorrect spelling, explanation: differant is not correct for a couple of reasons. First, the word-formation processes used to create it. The word is made out of the verb differ and a suffix -ent, used to create an adjective. There is no alternative version of the suffix -ent. On the other hand, differant would also call for a different pronunciation, which is why it’s an incorrect word.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling