Hilary already gave an explanation, but I just want to comment on a couple things.
Grammatically, your question isn't wholly incorrect, but most people would not use "discriminate" in this context. It would be more common to say "tell the difference" or "differentiate." So, you could ask:
"Can you help me tell the difference between each of these words?"
"Can you help me differentiate these words?"
"Discriminate" is a bit more formal, I'd say, but the meaning is about the same as "differentiate." It also has a negative connotation which is more commonly known. In a negative context, it can mean to unjustly show bias toward someone or something based on specific characteristics (race, age, gender, sexual orientation, etc.)
Also, you should say "Are they positive or negative?" OR "Do they have a positive or negative connotation."
These are just some minor changes, but you would be perfectly understood either way. Good work. :D I hope this is helpful.