TAS and RTA

TAS - Tool Assisted Speedrun
Uses save states, frame advance and slow down to produce the optimal speedrun using strategies that are not used by conventional (RTA) runners.

RTA - Real Time Attack
Start from the first input which affects the file (Normally file select, some games use the game start up (eg. Reset) as the start), and ends on the last input that affects the file (Usually the final hit on the final boss, however some games choose a different point). You cannot pause your timer mid-run, even if you pause the game to take a break. Emulators may be allowed for some games, but some don't. However, Emulation tools are [for every game that I've seen (maybe not all games)] not allowed for proper runs.

So why are TAS runs not allowed for RTA leaderboards?
- Because the time for it to be made and the final run time are very different. Even if emulation tools are allowed, because it takes at least 250 hours to make a good 3h TAS, the final run time would be at least that time (assuming the TASer doesn't take any breaks whatsoever from starting the TAS to finishing it, which is highly unlikely).
However, because the runs use emulation tools a lot, they're not allowed for RTA leaderboards, they serve as an optimum time for an RTA speedrun given the strategies that are currently known.