A vegitarian does not eat any meat at all.
Pescitarian adds only fish to a vegitarian diet.
A Pesci-pollitarian adds fish & foul to a vegitarian diet. (There is some controversy over pork as it is not a red meat, but by definition is not included in this diet)
Vegan is another controversial term. So I'll list the 2 most common practices
1. Does not eat any animal durived products. Meat, eggs, dairy,etc
2. A strict vegan goes farther than #1 an will not use any animal derived products at all. To include leather, collagen lotions, animal tested products, etc.
Then there is the more recent label Flexitarian- this is actually an omnivore that observes a vegitarian diet most of the time.
My wife falls into the Flexitarian category, only eating meat products a couple times a month.