The price of Elements is far lower. It is something you can buy for $99.99 and if you also get Photoshop Elements, the package is only $149.99 (prices in US).
To get Premiere Pro CC you pay $19.99 per month. So as you can see, the price after even a relatively short period of time is quite different.
If you are looking to also use After Effects, or edit audio in Audition. If you want to color correct with SpeedGrade, then go with Premiere Pro which works well with these and eventually upgrade to the $50 per month package for almost all of the Adobe products.
If you are moving from iMovie, you will probably find that Premiere Elements is plenty powerful. It just isn't as powerful as Premiere Pro, especially when you consider the ability of Premiere Pro to work with other valuable programs.
If you told us specifically what new features you are looking for, we might have a better shot at a better answer than the one I have provided.