>>In the Microchip web site I couldn't find a chart
>>stating the features of each type.

>It's 00148a.pdf on http://www.microchip2.com/products/other/other.htm

What you want is http://www.microchip2.com/products/micros/
Click on one of the three catagories. These are regular html tables
not pdf so they don't take forever to download!