i don't know if there is a difference between Alopecia Areata and Seasonal alopecia. Both of them are "recurrent" events.
Seasonal alopecia is usually during the fall/winter months for most people. (male/female)..
What i've learned about AA (alopecia areata):
It's sometimes occurs as a rare a event when you're younger. But when you make the 40 mark. All hell breaks loose.
The bald spots are usually small, and are usually at the temples, crown back of the head. They range from round, oval, also known as "invisible" bald spots. dime-sized to quarter size.

Some people will notice these bald areas not only on their head but on their eyebrows/lashes.
(I noticed this specifically at the edges of my eyebrows)
Here's the clincher: When treated, the hair will grow back, and fall out again, then later stabilize. Some cases - it will just keep recurring if not treated.
In most cases, many people like myself have noticed their hair is "thinner" on one side than the other. No matter which side you sleep on.
(My right sometimes is the same as my left, then during the fall or winter months? It gets thinner thanks to the random bald spots that pop-up on the right temple/crown.)
The hair grows back eventually, then falls out again in random areas.