Sturridge is older than him and doesn't have the potential Nerman has. Nerman in time will create more for others than Sturridge and will score similar amount of goals to Sturridge.
Sturridge is a few years older, but being at Chelsea and City he has not played that many games for a player his age. And most of his appearances were just short cameo roles off the bench.
Sturridge has played 123 (132 if including international) games in his career with most of them being as a sub.
Neymar has played 119 (165 if including international).
Experience wise they are arguably at a same level of development.
With regard to assists, Sturridge has 3 this season. Obviously Neymar will have more (8) due to his position. Sturridge has picked up his assists when playing along side Suarez, and for a lot of the season they have been unable to play together for various reasons (ban, injury). I would expect his assist count to increase if both stay fit and in the team.