Correct spelling, explanation: original Latin word points to correct spelling distributor (as in core verb to distribute). It is spelled without the vowel i before ending tor. When we want to talk about a person who does certain activity, we add suffix -or to the verb, thus we receive distributor.

Definition of distributor:
noun, a person or thing that distributes something
You can have a part-time job, for example as a leaflets distributor.
We had to call the plumber because the water distributor leaked.

Incorrect spelling, explanation: this form is incorrect, because there is no extra i in the core verb, that this word derives from distribute. To create a word describing a person doing a particular thing we add suffixes -or or -er to the verb talking about the action, therefore distribute with the suffix is distributor and not distribuitor.

Incorrect spelling

Incorrect spelling

Incorrect spelling