Some 18F nomenclature but in German, so maybe use google translate?
All the PIC32's have a 'part number decoder page' for example page 328 "PRODUCT IDENTIFICATION SYSTEM" in PIC32MX1XX/2XX
or page 656 "PRODUCT IDENTIFICATION SYSTEM" in PIC32MZ Embedded Connectivity (EC) Family
AFAICT, all PIC datasheets have similar part-number-encode/decode pages. However, I'm only interested in PIC32.
Wikipedia PIC microcontroller/Family core architectural differences
That divides the families by instruction size, and gives a useful summary of the 12bit, 14bit, enhanced 14bit, 16bit, 16bit dsPIC, PIC32 devices. Like many other microcontrollers, the 'natural' data size and instruction size can be different.
I'm not a PIC24 person. Looking at the datasheets for PIC24FJ256GB210 and PIC24FJ256GB110, PIC24FJ256GB210 has 96kB RAM vs 16kB RAM for PIC24FJ256GB110
Typing the part numbers into "Search Microchip" at Microchip usually gets to a brief summary of the part, and links to more information.
For example PIC24FJ128GA010
Typing the part numbers into "Search Data Sheets" at Microchip will get to the device datasheet directly. Data Sheets usually has a summary of each family part on the first real page (page 3?). The table is often good enough to compare across similar families, and identify the differences.