> The people who are calling to defund the police literally mean defunding the police.
The people who are saying defund the police do want that literally, but they don't mean “reduce funding to zero”, they mean reduce funding and responsibility and transfer the bits that aren't optimally served by an armed paramilitary law enforcement force to be served by other agencies, who also get the associated funding.
There are people who take that a step further, who prefer the slogan “dismantle the police” or “abolish the police”. Mostly, like the “defund” group with which they overlap (these are variations rather than strict alternatives) they want to fund agencies that they see as more appropriate for the functions, but the dismantle/abolish group thinks that the kind of centralized armed groups with paramilitary organization that exist as local police departments aren't the right solution to any problems (except perhaps for large scale civil disorder, but we already have the national guard to respond to that, who don't do nearly as much to provoke that disorder in the first place), so they think all the functions of existing police departments should be transferred to other agencies (some of which might have arrest powers, and even armed agents, but those agents would be working for domain-specific agencies, not a massive centralized general-purpose paramilitary law enforcement agency.)
> Presumably the ones that make this call are hoping an ideological paramilitary arm (such as antifa) can fill the power vacuum left behind.
No, for the most part the defund/dismantle/abolish group thinks that the problem is centralized omnipresent paramilitary forces with a separate ideology and culture from the general society, not that we just need to swap one out for a different one.
> Those that want reform are asking for reform.
“Defund the police” and “dismantle/abolish the police” are approaches to reform of how society serves the functions currently served by the police. They are approaches differing from the counterproductive “reform” efforts that have led us where we are today because they don't involve shoveling more scarce resources and more responsibility into local centralized paramilitary law enforcement agencies.