My husband's grandpa wants us to visit him in Oaxaca, Oaxaca. Is food anything like southwest US mex food?

There is a big difference between Texmex and real mexican food. The real mexican food it's very spicy, with a lot of chilli. It's delicious the food in Oaxaca, it's marvellous. I recomend to eat in a market place "sopes", "gorditas", "mole" (there are a lot of moles, black mole, yellow mole, and red mole), tamales oaxaque帽os, chilaquiles, ufff, there is a lot of delicious food in Mexico.

Maybe a bit similar but ethnic food is always different. Not to mention our food is catered to our own tastes.

Why don't you just ask him about the specifics? I'm sure he'll tell you what its like.

TexMex food and real Mexican food do not resemble each other at all ... no matter what part of Mexico

Unfortunately not!, I am from south Mexico (Veracruz) and I live in new Mexico, food over there is not like the one you get here in south Mexico !!
It is like eating a cake that you baked at home and eating one from a fast food restaurant. BIG DIFFERENCE!
But I believe in Oaxaca you will get the best!! specially its chocolate!!

dont know

Mexico, Oaxaca especially, has some of the best food in the Americas! You will love Oaxacan cheese, chocolate, and of course mescal. Mescal (like tequila but MUCH better) originated in Oaxaca. If you have time, travel to Puerto Escondido, Oaxaca. It's a beautiful little villiage on the Pacific. No Mac Donald's or Blockbusters, lots of surfers, few Americans but many Europeans, Australians and Canadians (and Mexicans of course). Three different beaches in one little town give you three totally different experiences (surfing, swimming, and clear-water snorkling). I'm jealous!

Not even. The one you find here never tastes authentic. You will find such good food in Oaxaca, I guarantee it.

No, it is much better in Oaxaca. Lots of spicy sauces. Many people in Oaxaca eat live insects.