hi Boji,
I cant give you the full list of differences in terms of Red,Green, Yellow ,the yellow is the nutty satay style one , coconut milk is common to all too .
I use a paste called 'Blue Dragon' , not sure if that brand is available stateside . Tin of cocunut milk and maybe quarter to half a jar of said paste ,and the meat or veg ,its really as simple as that , if I want more the yellow curry style adding a spoon or two of peanut butter and some crushed roasted peanuts give the sauce great body . I think the main difference between green and red is red vs green chilli . I think the red has tomatoe in it too
Any Asian supermarket should have some variety of Thai paste , not sure how common Asian food stores will be in your neck of the woods ,so it might involve a trip to the city or something like that .
Fish sauce is the another key ingredient ,its more or less used as seasoning along with soy sauce ,end of day the pastes have the seasoning added already ,but its handy to have the fish sauce to hand as a seasoning adjuster . Tinned salted anchovies ,like you get on a pizza are a great substitute for fish sauce ,in the final taste test you dont notice the fishy element ,its subtle and in the backround . So for starters ,a jar of good green paste and tins of coconut milk are the only special ingredients you need ,Id imagine almost every house there has peanuts and peanut butter , so you have the ingredients for two out of three Thai styles in that lot . Oh one more thing ,as Leut.Colombo used say ,if you like the idea of fruity and slightly more sweetness in your Thai curry ,you could try adding mashed ripe mango , Your dinner guests will be singing your praise all around town Im sure ,let us know how you get on.