In the UK we almost exclusively talk about CVs and not resumes (Rez-oo-Mays) and would consider the words interchangeable.
In the US it is different, and they are distinct.
The resume is a very short (typically 1 page) summary of job experience and qualifications specific to the role you're going for.
I.e. It's the brief answer to the question "why should I hire you?"
They typically may include a section on career goal / objective, and their aim is to make you stand out from the crowd if the reader is only given a few seconds to decide on who to ask to interview.
The CV, on the other hand, is intended as an objective detailing of accomplishments, primarily academic, and so is generally much longer, with the expectation that the reader will actually read the detailed content rather than the sound-bites of a resume.
Imagine the CV is like the full business case, and the resume is like the advertising pitch.
But as said, in the UK we really on deal in CVs, and they're probably a half-way between the US resume and US CV.