Influenza A is further divided into subtypes. You may have heard of H1N1 or H3N2 – those are the two dominant types of influenza A circulating right now, according to the CDC.

Flu A tends to cause more ear infections than flu B, but type B is associated with more seizures, vomiting and diarrhea, said Dr. Sherif Mossad, an infectious disease doctor at the Cleveland Clinic.

It's flu season, but not all influenza is the same. If you're feeling sick, it helps to know the difference between flu A and flu B symptoms, experts say.

Influenza, in contrast, is far more selective, driven by Type A and Type B influenza viruses. These strains, particularly notorious ones like H1N1, mutate rapidly and trigger unpredictable outbreaks.

What is the difference between flu A and flu B? Experts on the symptoms What to know about the major flu types as respiratory virus season rages on.

All flu vaccinations this year will guard against two Type A flu strains and one Type B strain. Another once-common form of Type B flu quit spreading a few years ago and was removed from the vaccine.

Influenza A is more commonly seen earlier in flu season, in the winter months, while influenza B seems to crop up later, around early spring.