Ritual of Summoning reads "Sacrifice a character to place a success token…"
Ritual of the Lance reads "After you sacrifice a character, place a success token…"
There's a huge difference there, right? No just different wording of the same trigger.
Yes. In the former case (RoS) sacrificing a character is a cost to be payed to trigger the effect. In the latter case (RotL) it's a side-effect that you can benefit from whenever you sacrifice a character for any reason, e.g. when paying the cost of RoS, i.e. if you have both Rituals in play and you trigger RoS, you get to put a success token on both Rituals.