I see a "rework" as a gameplay-shattering change to an existing champion to the point that their playstyle becomes noticeably different to the player and the spectator. By extension, a change of playstyle is when something about their lore-related thematic play pattern - usually mechanical but also includes play style - changes hopefully for the healthier and more appreciative - e.g. Poppy (character and kit change), Warwick (kit change), Sion maybe, and hopefully the product of the upcoming Urgot rework. Other reworked champions do not really fit this criterion, since either their lore remains untouched except for some added detail or update due to the death of the Institute of War, or their new kits weren't all that different (e.g. Fiora, Yorick, and Taric). For example, Fiora's ult change was simply "let's turn it from a multi-target target point-and-click ability to a single-target debuff designed to fit her character better as a duelist", which would thus classify itself not as a rework, but more of a "coldfix", in contrast to the term "hotfix".
There is a perceptible difference between "let's update the playstyle of a champion as our design philosophies involve" and "we didn't design our champion to allow its players to feel like they are the character, so we're changing aspects of it so the vicarious experience can be attainable". It's like the difference between editing and composing, both of which I'm doing in these paragraphs to give you a somewhat readable comment post. So, let whatever involves composition be placed in its appropriate place: Concepts & Creations.