I am confused between these words. Dictionaries say they are similar, but I vaguely remember my schoolteacher apprising me of a difference between them. I would love if someone could elucidate.
Comical - Humorous, lighted-hearted situation or behavior inspiring amusement.
Comic - In contrast to tragic. From the point of view of the ancient Greek dramatists, tragedy had to involve the fate of a great personage, e.g. a king. Comedy on the other hand, dealt with the common people, the masses. To this day, this formula remains intact in that comedy as a form of entertainment is largely intended to appeal to the masses. The behavior of such lessor figures was felt to be amusing from the point of view of tragic figures. Hence, comical is an attribute often assigned to comic.
"The behavior of the masses is truly comical."
Irene's, Mustafa's, and Jack's distinctions ring true, and those are indeed many of the invited inferences that cluster around these two words. There are more, and more ways to talk about them.
Comic occurs most often in generic terms, like comic opera, stand-up comic, a pile of comics (cf a couple of comics, a pair of comics), referring to things or events or actions or images(, etc.) that are intended to be deliberately funny -- to make other people laugh. It also refers to the people doing the intending and the acting, etc; and to the socioeconomic system that is implied by such artifice. It's Artificial, not natural.
Comical, on the other hand, seems to refer exclusively to amusing Natural things, etc. Stuff that really happens; shit my dad says. I don't think they need to be ludicrous or absurd; those are extremes on the humor spectrum. Even gentle irony can make one laugh sometimes. I agree, though, that excess absurdity or boffo ludicrosity often makes the laugh bigger.
When it's natural, anyway. But not when it's obviously contrived, which seems to be the point.
That said, I'm afraid the bad news is that this generalization does not generalize to other such pairs. The -ic/-ical derivational suffix, which derives an overt adjective from a noun (or from something else; it's a sloppy affix), appears mostly with -ic (10,903 words), but also often with -ical (2,619 words).
Most (but not all) of the -ical words appear also in the -ic list. And there isn't much, if indeed any, systematic pattern visible to me from a desultory inspection of the isolated word lists. But maybe there is one. Anyway, there they are; data is always preferable to speculation.
(By the way, these lists were extracted from a "wordlist.txt" file that was the spellchecker dictionary on the University of Michigan faculty email system for a couple of decades. As explained here)
There's no inherent difference between the two words themselves, but it's important to note the two broad shades of meaning - relating to humour and funny (ha-ha).
In terms of actual usage, comic is far more common in general parlance today for both senses, but some people may think the longer form comical is somehow more "emphatic" for very amusing.
Also note that there are certain "stock terms" such as comic writer/comic actor which imply the first meaning above. It's always possible that if you met someone thus described, they wouldn't say or do anything particularly funny (when they're not "at work"). If you ever did hear of someone described as a comical actor, you'd probably expect him to be more consistently funny.
You characterise something as comic when you want to say that it is funny. A comic monologue, for example, is meant to make the audience laugh. This word is used especially to talk about writing and drama or things that are funny in a deliberate and theatrical way. It is not used to describe people (except for comic writers).
Comical, on the other hand, is again something funny, but in a ludicrous or absurd way. A series of comical misunderstandings, for example, make you laugh because they don't look like they could really be happening, yet they are.
Comic is connected with comedy and refers to "a characteristics". Comical usually have a sense of "fun" as a result of "strange" and/or "unusual" happenings or situations.