We say season 4, season 5, etc. You guys say series 4, series 5, etc.I dunno about that. I've seen it sometimes and that's confused me. We have the same base property, but it'll be a new series. There can be a few seasons of a series, and then it will change - see Star Trek, or perhaps Dr Who. Same thing, but different series, usually after a reboot or extended time off the air.
In Ireland everyone calls them seasons anyway.
And after reading series so many times it's now lost meaning to me