Giga Chad as a concept promotes being at peace with yourself, bettering yourself and making yourself a better person in society.
Chuck Norris as a concept mostly promotes toxic masculinity and “being badass”, a proclamation of toxic superiority that is unattainable.
Giga Chad as a concept is used by whoever wants to use it to justify anything they want by saying “'cause I’m a Chad”. In the same way that Chuck Norris did. 90% of the memes for each can be replaced with the other and lose almost no relevance. Someone can use a giga Chad meme to say “women’s rights are a joke” and the same for Chuck Norris. They can also say “defending the homies when they want to share their feelings to the bros”. I’m not saying the Chuck Norris memes are guilty free or whatever, but the giga Chad memes are far being used only for “making yourself a better person”