In America a resume is basically a slightly shortened CV. But from my experience (as someone who has lived and worked in IT in both the US and the UK) they are nearly identical. They both summarize your work history in almost identical styles. But the resume is preferably limited to 2 pages maximum, while a CV can be longer.
I don’t recall ever having both a resume and a CV in the UK and initially applying with a resume and then bringing the longer CV to the interview. It was just a name and length expectation difference that separated them.