it all comes down to access times. hard drives are slow. like an old cassette deck, skipping ahead takes a while, while the ipod jumps to the next song. or the last song instantly. they both play music but how fast makes all the difference and that difference is the storage medium.
the faster you can get windows from the drive to RAM the faster windows boots. HDD's are slow like a bicycle, SSD's are fast like a motorcycle. the trip is always faster in a motorcycle than a bicycle.