Most people can breathe in pollen, dust, and dander with no problem. But for people who are allergic to these ordinary everyday things, these substances present more serious consequences. They set off a complicated chain reaction in which the body works hard to expel them. That's why your nose runs, your eyes water, you sneeze and cough. Even for doctors, it's often hard to tell, because the symptoms are so similar.
Colds usually begin with a sore throat, or turn into one somewhere along the way.
Allergy symptoms often develop one at a time. For example, first a runny nose, and then, days later, watery eyes. Allergy symptoms usually linger for a much longer time. Either that, or they can disappear overnight as soon as you remove yourself from exposure to the allergens. You can't change the weather outside, but you can change the environment inside.