What’s the name of two words that are put together to make another word, e.g., mobile phone, chewing gum, or credit card. I’m not sure if these would be classed as portmanteau, compounds, or something completely different, as the words are still separate and not conjoined.
Those are compounds. From [Merriam–Webster]((//www.merriam-webster.com/dictionary/compound):
a word consisting of components that are words (as rowboat, high school, devil-may-care)
That they are spelt with a space in between the components is just the way English orthography works but does not affect the grammar or classification. E.g., the German language allows forming compounds in the same way, but they are always spelt as a single word, e.g.:
Mobiltelefon = mobil (mobile) + Telefon (phone)
By contrast, in a portmanteau, the components are fused such that there is no clear delineation where one component ends and the other begins. For example, if people began to say mone instead of mobile phone, this would be a portmanteau.
If you want the names of the 2 separate words, what about "attributive adjectives" and nouns? In your examples, the first word are all attributive adjectives (adjectives that describe and appear before a noun) and the second word is the noun being described.