Warhammer 40K Tabletop XII: "Now in Rapid Fire range!"

[Hootman]

lightning claw...Xpts
Power weapon..Xpts

so this space marine noobs has to ask: diference?

First of all, never EVER post the individual costs of wargear. EVER. GW doesn't like it, and there are forums that have been forced to close or are otherwise interfered with because people were revealing individual costs of gear.

To answer your question now:

Power Weapons (Powerswords, etc) deal wounds that ignore normal armor saves, and when weilded with an 'Additional Close Combat Weapon' (normally a pistol or a combat blade), grants an extra attack.

Lightning Claws are special powerweapons that ONLY grant extra attacks when paired with a second lightning claw. Lightning Claws also get to re-roll any failed roll to wound.