Or more simply put;
sexism: males as superior and females as inferior
genderism: males as masculine and females as feminine + masculine as superior and feminine as inferior
Genderism is the marketing and sexism is the product.
Genderism is there to obfuscate and package a clearly outrageous and indefensible socially constructed deeply political and unscientific notion as something normal, natural and inevitable.
Sexism and genderism have been around since forever - trans ideologists / queer theorists / etc didn't invent these concepts. Male supremacist society did.
And feminists didn't start resisting gender when transgenderism took off. We've been resisting it all along (because it is the marketing department of sexism AKA patriarchy[.
It's just more narcissism / lack of critical thinking / lack of self-awareness / navel gazing / dehumanising of girls and women / woeful ignorance of women's history on the part of the transgenderists that they seem to think that being "gender critical" is anything new and that it came about because of transgenderism.
Transgenderism is deeply conservative, deeply patriarchal, deeply sexist and deeply anti-woman; all things that feminists are deeply against no matter who is manifesting them.
And the above are all things that misogynists are totally into. Hence the success of transgenderism. It isn't because lots of people actually believe in it or care about it. It's because it's sexism / genderism on steroids packaged as progressiveness. It allows people to be ulta sexist and ignorant whilst simultaneously virtue signalling about how right-on, progressive, inclusive, enlightened, modern, intelligent and superior they are.
Win win for patriarchy. Lose lose for women. And juggernaut of support and veneer of acceptability for a regressive, sexist, homophobic movement which does terrible things to children, vulnerable people, the gender nonconforming and, of course, women.