Is the /k/ in "keep" differant than the "/k/ in "coop"?
/k/
There are English dialects which have the allophones [c] and [c_h] of /k/ before front vowels. Consequently, one can find dialects which will realize the /k/ in "koop" /ku:p/ as [k_h] but the /k/ in "keep" /ki:p/ as [c_h].
However, there are very many English dialects, such as that here, which have little to no fronting of /k/ before front vowels. As a result, a large portion of English-speakers will use the same realization of /k/ in "keep" and "koop".
However, there are very many English dialects, such as that here, which have little to no fronting of /k/ before front vowels. As a result, a large portion of English-speakers will use the same realization of /k/ in "keep" and "koop".
Yes, they're different, but only slightly. In English phonology you would only bother with the /k/ pronounciation, but if you get down to the specific allophones, when preceeding front vowels, /k/ is pronounced /c/. (I think /c/ is the correct symbol for the palatalized version)
Hate to be pedantic but the correct symbol would be "[c]" not "/c/" since it's an allophone rather than a phoneme.