Unless otherwise stated in the device specifications, there is currently no reason to suspect any functional differentiation between the 11" and 13" models. The only obvious technical differences between the new iPad Pro models are the M4 CPU itself...
Both the 11" and 13" models with 1TB or 2TB internal storage have an additional high-performance CPU core (i.e., four high-performance cores - as opposed to three).
In common with all preceding models of iPad, be aware of fundamental functional difference between WiFi+Cellular and WiFi Only models. Aside from the obvious Cellular functionality, only WiFi+Cellular models include GNSS/GPS location capabilities - which may impact any Apps or features that require accurate and consistent location data, such as Mapping.