So, what's the difference between an iPad with WiFi and an iPad with 3G plus WiFi. It's a question that seems to come up frequently, so I thought it would be worth finding out some answers to the question.
I've found five major differences between the two models and keep on looking for more. Here are the five differences:
Number 1: Limited connectivity vs. Extensive connectivity . With the iPad WiFi your connectivity to the internet is limited to areas where you can access the web via WiFi. With the 3G version of the iPad you can connect both via WiFi or the 3G cellular network. That means it should have connectivity anywhere you get cell phone coverage. To get the same coverage with the WiFi version you would need a portable WiFi, like Verizon's MiFi or some of the smart phones that can act like a WiFi.
Number 2: You Pay for More Connectivity . The 3G iPad costs more to buy. At the time I write this, the difference is about $ 130 in the US. To use the 3G wireless service you need to have a wireless data plan with you carrier. In the US, AT & T provides data plans for a price. To start they had a $ 14.99 per month data plan with 250MB of data included and a $ 30 per month "unlimited" plan. The unlimited plan was discontinued pretty quickly and now you can get 2G of data for $ 25 per month.
Number 3: iPad with 3G also has built in GPS service . The WiFi version can do some triangulation; you need a 3G iPad to get a really accurate location fix.
Number 4: Some small physical differences . On the back of the 3G iPad there is a black plastic section that enables the iPad to get a better connection to the wireless network. The 3G version also has a door on the side for you to insert the Micro SIM card. These differences are probably not that big a deal given that you will probably want to use an iPad cover to protect your iPad.
Number 5: Shorter Battery Life for the 3G . Using the 3G network chews up more battery. From what I have read it cuts battery life from about 10 hours down to between 7 and 8 hours. Not bad, but it does count at the end of a long day.
So to sum it up, if you are just using the iPad around the house, get the WiFi version and if you need to use it out in the field you are probably better off getting the 3G version of the iPad.