what is the difference between red fadc and ex fadc

[Applethal]

the only difference i know is the amount of bars consummed , red takes 3 and ex takes 2 bars
but i see many people on youtube making red fadc combos instead of the ex one , why ?

[Rikkore]

red fadc guarantees a crumple while an ex just hits

[JasonS]

If you hit with level 1 Red Focus Attack, you cause a crumple without having to charge up.

So for example, for Yun if you do cr.MP, cr.MP, LP Shoulder xx Red Focus Attack (release) you get a crumple into ultra or just more meterless damage.

Red Focus "FADC" is pretty worthless but doing a Red Focus Cancel into hitting with the level 1 red focus attack gives you huge damage potential.

[76561198114094360]

Before anything, Red Focus Attack costs only 2 bars, when done at neutral, while regular/normal Focus Attack costs nothing. EX version (when a move is cancelled by a Focus Attack/Red Focus Attack) of regular Focus Attack costs 2 bars while EX Red Focus Attack takes 3 bars.

Both regular (non EX) Focus Attack and Red Focus Attack have the same frame data, can be cancelled with a dash (forward or backward) on hit, on block or while still charging before reaching Level 3, and are vulnerable to Armor Break moves and throws.
They both leave you at frame disadvantage after a Dash on Lv.1 whether it hits or is blocked -- unless you play Chun-Li or Makoto (generally between -3 and -1 -- frame data is the same on hit and block), grant frame advantage after a Dash on block and a Crumple on hit at Lv.2, and are unblockble at Lv.3, witch also grants a longer Crumple than Lv.2 if they connect.
Either Focus Attack type scales down by 20% in a combo.

On the non EX versions, the difference is that, regular Focus Attack can absorb only one hit (it has only one hit of Hyper Armor) while Red Focus Attack has an infinite number of Hyper Armor and deals 50% more damage.

EX Focus Attack is just the same as its on EX counterpart, without the Hyper Armor, and it just costs 2 bars because you are interrupting and cancelling the recovery of something (even a LP).
Because EX Focus Attack is the same as Focus Attack, it also is disadvantageous on hit, and is best used in conjunction with a Dash Cancel (doing an attack, cancelling with EX Focus Attack then cancelling the Focus Attack with a Dash - EX FADC).
Some characters have attacks that produce enough hit stun for a Level 2 EX Focus Attack to connect (Ken's EX Hadouken in the corner for example) so it can be used to get a Crumple and follow with any combo, but not all characters have it and it's highly situational and distance dependent.

Why EX Red Focus Attack is great, is because it causes a Crumple on Lv.1 (witch leads into a solid, big combo) and adds that 50% damage on top of it, so it has more overall reward than EX Focus Attack for one more meter bar.
The down side is that only few moves per character have enough hit stun on hit to allow it to hit as a combo.
For some characters the only move that can lead to it is not very reliable (poor Ibuki :( ), and for others, it opens up a huge new source of rapid, easy damage (Spanish Ninjas are much more luckier -- Vega Air Lines!! XD )
EX Red Focus Attack also doesn't have a Hyper Armor.