Is there a term used to signify one dialect retains more older words, or conversely, that one adopts more neologisms?

Sometimes English retains an old word and updates it meaning, like bottle which originally meant wineskin. Sometimes it creates a new word for a new innovation, like television. There appears to be a tendency in British English to retain some older words for new purposes where they have been replaced in American English with neologisms. For example torch/flashlight, chemist/pharmacist, dustbin/garbage can, fire/heater.

Is there a term that we could use to say one dialect retains more of the older words, or conversely, that one adopts more neologisms?

Examples sentences where it would be used:

British English is a ______ dialect, unlike American English. (or vice versa)

Or, British English is more ________ than American English. (or vice versa)

Linguists talk about languages and dialects which are conservative, preserving old forms from the ancestral or "parent" languages, or in contrast those which are innovative or advanced and have new forms different from the ancestral languages.

See the Wikipedia article on linguistic conservatism. There is also a related question on linguistics Stack Exchange.