Blue Essence = IP, you can buy more things with it than you used to. RP is still used for skins.
Runes were removed, and the new mastery system replaces it, if you bought runes, you got a refund in Blue Essence and some mystery skins.
Maps really aren't much different, 3v3 is more or less the same, ARAM if you weren't around is just what it always has been. All Random, All Mid. It's a one lane map, everyone gets rolled a random champ. Then you get tossed on a single lane map, and can't buy after leaving base until you die.
Summoner's Rift was made a lot prettier. Dragon received the most notable change. Instead of just rewarding xp and global gold, they took the gold reward away and instead dragon gives you a buff. Dragons are random each map.
Infernal: ap/ad
Mountain: +Dmg to structures
Wind: +Move speed out of combat
Ocean: + Out of combat health regen
After 35m Elder Dragons spawn. This grants +50% to any previously received elemtnal dragon buff, and 45xNumber of Dragons Killed tru damage to attacks/spells.
The only other change is that in the baron pit before 20m, a Rift Herald spawns, which if killed gives you a trinket you can use once per game which gives you a giant monster to help siege down towers until it's killed.