For most teams, the difference is the top 5 kids. A competitive elite team typically has a top line/pairing that make the team. Top line of a competitive platinum team is generally interchangeable with the middle and bottom of an elite team.
If even "most" of the players were actually elite, New England would be sending hundreds of kids to D-I & D-III at every birth year.
Everyone's situation is different, it is difficult for others to tell you what is best for your kid and family. My kid moved from a bottom black/platinum to a bottom elite and then to a top elite team. The difference in talent level and work ethic of the players is noticeable every time he moved up. The same can be said about coaching. In the end, very few kids in the EHF elite division are able to continue on to play on top U14/midget teams. My suggestion is to figure out what your kid needs at his current stage of development and do not worry too much about labels.