When it comes to changing a moving picture’s frame rate whilst keeping the title’s original duration, a simple speed change just won’t do it.
For this purpose (but not exclusively) a frame rate conversion is required.
If, on the other hand having a title with different durations between versions won’t be of concern to you, then a simple speed change might be all you need.
Although, please be aware that with speed changes (opposed to frame rate conversions) comes altered audio pitch. Many platforms correct the audio pitch but these are never flawless.
If your project, for example, is focused on audio content such as music, showcasing musical artists and their performances, then it is strongly advised to stay away from speed changes and go for a frame rate conversion instead. This will ensure the audio mixes stay intact and exactly as it were intended to be listened to.
