Gelatin and gluten are two different things and should not be confused with each other.

Gelatin or Gelatin:

Gelatin or gelatin is a colourless and flavourless food additive which is derived from animal bones or other body parts. It is commonly derived from pigs.

Mostly it is represented by emulsifier or e-number E441 (Gelatine). So, Muslims should certainly avoid this and also some other haram emulsifiers.

Gelatin is commonly used in chocolates, jelly, ice cream, cakes, protein powders etc.

Gluten:

Gluten is totally safe and halal. It is a group of proteins and found with starch in cereal grains, wheat, rye, spelt and barley.

The two major proteins in gluten are glutenin and gliadin. Gliadin can have some side effects on certain people.

When wheat flour and water mixes, they form a sticky mixture due to gluten. The glue-like attribute makes the dough elastic and makes the bread rise when baked. The name glu-ten is also derived from the glue-like quality of wet dough.

Gluten causes some health issues for certain people, which include celiac disease, gluten sensitivity, wheat allergy etc.