i have heard of it, but dont know what it means. 
read:
ok. how r the prices vs quality?
The price on splined cranks aren’t too bad, but are still a little pricey.
They are so worth it though, the strength and durability you get from a splined hub/crankset will pay for itself again and again and again.
EDIT: 8k post. Go me. lol
Man I remember when I asked this way back in the day 
Wel its a diferent design =p. Well there are Cotterless cranks cottered cranks, and Splined cranks. Cotterless is the most common, and the strongest is Splined(we wont go into the evil known as cottered). Cotterelss cranks have one bolt that screws into the square tappered hub. A splined crank bolts on the same way but sometimes has a bolt on the side to close the crank on even more… Here are some pics m8…
Here are your regular cranks
here are splined cranks
If you notice the part that bolts to the hub, cotterles just looks square and splined has ridges that give a more snug and supportive fit…