What's the difference between ROTH IRA and Traditional IRA?

Can I take money out of ROTH IRA anytime I want without paying tax?

Yes Roth IRA's allow withdrawals at anytime up to the total amount that an individual has invested. It also os exempt from any tax or penalty upon wihtdrawal.

If any portion of a Roth IRA is derived from converting from a Traditonal IRA, only the amount that was present before conversion can be withdrawn.