What is the grammar diffrence between the these words?

Question

"compran and compren"

Example "Las personas que compran y hacen la comida"

Why could I not use compren ?

Answer 1

Compran is in the indicative mood, compren is in the subjunctive mood. The distinction between these two moods is very important in Spanish.

Helpful articles can be found on this site, especially here:

Subjunctive vs. Indicative

Answer 2

"Las personas que compran y hacen la comida"

As JDB1920 said, compren is subjunctive. If you are talking about folks who you know buy and make meals you should use the indicative, as above. If there is a question about whether there are such people or about whether they do those things you would use the subjunctive in both verbs: "Las personas que compren y hagan la comida" .

If we had the full context of your phrase we could give you a precise answer.

Cuando la gente tratar de bromear acerca de las personas que trabajan en lugares como McDonalds son tontos y las mismas personas que comen y compran la comida todo el tiempo - Sc89, Sep 22, 2014