it doesn't have many differences between "gente" e "pessoas". In most of situations you can use them like synonyms.
The both words means a group of persons. But when you use the word "pessoas" you have to put the sentence on plural. And when you use the word "gente" you have to put the sentence on singular.
Ex. There are many people here.
1) Tem muitaS pessoas aqui
2) Tem muita gente aqui
But the word "gente" can also be used to refer to a group of people that includes you.
Ex. We are going to the movie. ( A gente vai ao cinema) or (Nós vamos ao cinema)
Let's go with us (Vamos com a gente)