Visually, it is not possible to differentiate between the two configurations with 3G capability. It also can be easy to mistake iPad 2 models for other iPad models.
If you are on a tight budget and cannot afford a newer iPad model -- which would be better, naturally -- the iPad 2 models are worth consideration although they likely will not have current iOS support for much longer.
The 9.7 and 12.9-inch iPad Pro models will look immediately familiar to anyone who has used an iPad Air 2, as both take design cues from Apple's 2014 tablet. The 9.7-inch iPad Pro looks almost identical to the iPad Air 2 while the 12.9-inch iPad Pro looks like a larger version of the iPad Air 2.