Both amp seems similar to me. Is there any difference between them or it's just the company tackticks for selling. Which will be good for home practice?
It looks like the only difference is the 15X has OVERDRIVE, DISTORTION, METAL, METAL STACK while the 15XL has OVERDRIVE, DISTORTION, METAL ZONE, EXTREME.

Not sure on the difference between metal/metal stack and metal zone/extreme

Although, if you're looking at purchasing one of these I'd suggest one of the rolands that has modeling of other amps, it's very versatile especially on a budget.