[shooter88]

Ive never compared the two and was thinking about getting an sks cause there cheaper but dont know if its just a better idea to buy an ak...

[SSGN_Doc]

The SKS was a predicessor to the AK. It has a fixed magazine of 10 rounds and feeds from stripper clips. It has a gas piston with an intermediate piston that drives the bolt carrier back to eject and feed rounds. It features a folding bayonet that is a part of the rifle.
Yugoslavian versions of the SKS also feature grenade launcher with grenade sights and a gas shut-off for launching grenades off the barrel.
Most SKS rifles are made from milled receivers and have a longer sight radius than the AK.
There are a few Chinese versions that were modified to use AK mags. There are aftermarket detachable mags for teh SKS, but they can be a pain and you also have to worry about 922R compliance and keeping parts count up.

The AK was designed to be produced at lower cost and in high volume. It was designed to use a stamped sheet steel receiver, but there are versions that were made with milled receivers. It uses a piston that is directly attatched to the bolt carier and has a rotating bolt. It was designed from the beginning to use detachable mags.

[SSGN_Doc]

I'll add that the AK is designed to be a easily maintainable rifle in the field. It is shorter, and pretty handy, and as a high volume lead spitting tool it is easier to maintain high volume fire with the AK.

[kryptar19]

The SKS was made in 1944 by Simonov to fit a CARBINE role using the new 7.62x39. It runs off of a long-stroke piston and a 2 piece free floating bolt design. It is a simple design and robust design with few parts. It also has a flip-out bayonet, and typically comes with a 10rd fixed mag, though some Chinese models have a 20 fixed mag.

The AK-47 is an ASSULT RIFLE chambered in the same cartridge. Designed by Mikhail Kalashnikov, this system runs off of a long-stroke piston and has a two piece rotating bolt. It actually wasn't perfected until 1959 when the AKM came out. Most "AK47's" you see are AKM's. AKM's have higher quality stamped receiver and a few other improvements, such as an angled muzzle break.