How do you differentiate "soft" CC from "hard" CC?

There are many different types of CC - Crowd Control - and LOL Wiki lays it out quite nicely

Loss of Control - Crowd controls are grouped into one of two categories depending on whether or not the effect removes total control of the player's character. Hard CC completely removes all control of a character, while soft CC only partially removes it.

Hard CC

  1. Airborne
  2. Forced Action
  3. Stasis
  4. Stun
  5. Suppression
  6. Suspension

Soft CC

  1. Blind
  2. Disarm
  3. Root/Snare
  4. Silence
  5. Slow

Disruption - Crowd controls are grouped into one of two categories depending on whether or not the effect disrupts a channeled ability (such as Karthus Karthus's Requiem and Katarina Katarina's Death Lotus). Hard CC will disrupt channels, while soft CC will not.

Hard CC

  1. Airborne
  2. Forced Action
  3. Silence
  4. Stun
  5. Suppression
  6. Suspension

Soft CC

  1. Blind
  2. Disarm
  3. Root/Snare
  4. Slow

Movement - Crowd controls are grouped into one of two categories depending on whether or not they restrict movement. Hard CCs prevent all forms of movement, while soft CCs do not.

Hard CC

  1. Airborne
  2. Forced Action
  3. Root/Snare
  4. Stasis
  5. Suppression
  6. Suspension

Soft CC

  1. Blind
  2. Disarm
  3. Silence
  4. Slow

Each game develops its own terminology.
And even within each game, different people have different definitions of said terminology.
More specific term(s) would/could be: stun, root, snare, mez (and many many more)

But in general.
"Hard CC"
Complete loss of control over your character. This means you cannot move, cast spells or attack in any way for the duration of the stun. In some cases, your characters gets moved under control of another player (pulled, pushed)

"Soft CC"
Any form of debuff that restricts your movement (slow or root) and/or* restricts your attacks (unable to casts spells or heal or auto attack).

  • A root and a restriction on attacking would ofcourse result in a hard CC.