That's like asking if a red car is faster than a white car.
Frequency has nothing to do with data speed. Your limit is probably going to be your internet connection (from your internet provider ) - most routers these days are capable of going a lot faster than the data coming into them.
2.4GHz gets through walls better, 5GHz gets through smaller spaces (like wire screening) better, and there's probably less interference, because most of your neighbors are probably still using 2.4GHz. (And interference does slow down data transfer - but on the other hand, so does a weaker 5GHz signal going through a few walls that a 2.4GHz signal would penetrate better.)
But if you've got a 300mbps router and a 50mbps internet connection, the best download you can get is around 50mbps. The data flowing from the router to the phone will be going at 300mbps, but the router spits out a packet, then waits for the next one to complete before sending it to the phone, so the data thruput is the 50mbps of the connection. (And - other than speed tests, which is a special case - I've rarely seen a single connection, like a download, going faster than 3mbps. A 50mbps connection just means that you can run about 16 connections at "full speed" [3mbps] at once.)
Using the Cell Spot router that T-Mobile sent me I get about 50mbps on the 2.4 and 80 to 100mbps on the 5. I'm sure results will vary but those are mine. This is mobile only as other devices are older and are slower.