Yes I think it's only been since 100 Days began that the News Channel has taken the same programme also.
Yes, historically News 24 always did its own thing at 7pm.
When BBC4 started up in 2002, BBC World produced a specially branded bulletin focusing on international news and analysis, which was actually very good. Curiously, the programme was branded differently on each channel - it was "BBC World News" on BBC World and "BBC Four News" on BBC4. Somehow they managed to play out two versions of the titles simultaneously, although I've never been able to figure out how! Unless BBC World Pres had something to do with it? I think N9
used to play out the BBC4 branded version.
Anyway, It was (unnecessarily, in my opinion) refreshed in 2004 and became "The World" - in essence, only the set design changed and the titles/graphics colour scheme was changed from orange/red to green. Eventually it was replaced by "World News Today" in 2007 and replaced again by 100 Days/Beyond 100 Days more recently. It's only this latest incarnation that has also aired on the News Channel.