It's still a source of propulsion though.
They might differentiate but its not nearly as impressive.
for the general layman crowd, it's all the same.
For gearheads (and record-keeping), it's a very important distinction.
There are many different types of engines, and records for each type. There are even records of less than 300mph, but records nonetheless, all because of the exact type of vehicle and mechanics of the engine system of choice.
Naturally aspirated, supercharged/turbo'd, style of engine block, style of car, electric, rocket, jet engine, etc etc... each has it's own statistical records, and for good reason.
The developments that drive these individual records sometimes help in different industries, and different groups work on specific advancements for the purposes of breaking a very specific record and couldn't care less about the others.
Yes, they all are very fast. If that's all you are looking for with these events, than great, good for you. The differences are very important for the people who care about them though, because what gets put into exotic vehicles like these (which tend to be test-beds) can sometimes find their way into consumer vehicles.