Here are some differences between a cold and allergies.
A cold should disappear in about 10 days whereas allergy relief comes when you are no longer exposed to the offending allergen.
With a cold you will have a fever; allergies no fever.
Thick, yellow mucus with a cold; clear nasal discharge with allergies.
Body aches and pains with a cold; generally none with allergies.
Sore throat with a cold; scratchy throat with allergies.
I hope this answers your question. It can be confusing if you are an allergy sufferer. You aren't always sure when you have a cold during allergy season. Let me know if you need more information.