The first and main difference between those games.
COMPANY.
I remember Riot Games company in beta and first seasons. They were listen to people. They were consequent. If some problems appeared - they paid for them. When there were lags on server - we got recompense. When they did a mistake - they fixed it asap. Now? They are deaf to people. Very slow balance patches. When you think it is already +/- balanced they gonna change one thing (without proper testing it) and again 3-5 champs become OP or unplayable. OK I like changes, game must have changes, but it should be right. Tested. You know what is my pain in a*ss? That you make a mistake now (Like our <3 dynamiQ_Q and you wont admit that this was a mistake. NOOO, you will change it several times, you will make it more painful, but you wont tell us "We are sorry, this was our mistake". Guys responsible for changes ingame listen to me: YOU HAVE TO LISTEN WHAT PEOPLE SAYS. PEOPLE KNOW WHAT THEY WANT. IF YOU WILL BE SO PROUD AND DEAF THIS GAME WILL BE RUINED, YOU HAVE TO UNDERSTAND THAT LEAGUE WONT LAST FOREVER AND YOUR JOB IS IN DANGER IF YOU WONT DO IT PROPERLY. LEAGUE IS GETTING OLDER AND OLDER, YOU KNOW WHAT HAPPENS WITH OLD VIDEO GAMES.
And now Blizzard - Huge company. They made best videogames till this time. They did Diablo series, even if diablo3 was not as good as previous, they said sorry to us. They know it, and try to make it better. They listen to people, they answer people on forums, they talk with them all the time, they employed special people to read this CRIES on forums to know what to do in future.