>>38836794DP is a bit more open ended during the 3rd to 4th gym stretch. Platinum makes it more linear by making you fight Fantina right away, then forcing you to go up past Solaceon to Veilstone rather than allowing you to go to Route 212 from Hearthome (once you've reached Solaceon for some reason) if you so choose. Maylene and Wake are even the same levels in DP to compensate.
There's some really weird shit in DP though. Like how most of the cross-gens aren't in the dex, there's only two Fire and Ice lines, you get Strength before the third gym but you need the 6th badge to use it, and you fight Fantina way later than in Platinum, even after Celestic Town.