From the research that I recall from a decade ago when I was much more into BCI, I'm not sure there's a significant difference. And just like with a swipe-keyboard, accuracy will be hit or miss but be partially dependent on trained feedback mechanisms to hone towards a set of patterns.

Those that train on a BCI from an early age will "type" significantly faster and more naturally (as if at the speed of thought) than those that do not. There's a natural limit to idea-formation => symbol-formation => symbol-expression. Those that have trained on keyboards are able for this to fly from their fingers with only a slight delay; those that speak at something like "auction-speed" are mostly executing verbal macros: ie, it's just a single thought/action, highly trained so that it can manifest at high speed.

I can retype the entirety of the text above with just a few actions: cmd-A, cmd-C, ->, cmd-P. Performing a novel action, however, moves at a different speed entirely.