The Xoom product is one of the most competing tablets in the market. It is currently owned by Apple's iPad 2, and it comes in three different models. One of the models is the one that comes with Wi-Fi only, and the other is the one with 3G or 4G. The Xoom 3G/4G is actually more expensive than the Xoom Wi-Fi, and everyone that wants to purchase this wants to be sure if the pay really worths it.
One of the things that make the difference, and also makes the price worth it is the addition of modem hardware that enables the phone to connect to the cellular network. It's not really making any difference in the size of the phone. Another difference is that, in addition to the memory card slot, the Xoom 3G/4G also has a slot for a SIM card. It should be kept in mind that the Xoom 3G/4G will need a subscription for data connection, either daily, weekly, monthly, or whichever time frame; but the Xoom Wi-Fi can be connected to any Wi-Fi connection at any place.