Difference in free memory

Not a real problem here. just curious. I'm porting a sketch from an Arduino UNO to a Pro Mini and I noticed that when the sketch is compiled the UNO reports xxxx free from 32768 bytes where the Mini Pro gives xxxx free from 30720 bytes.
There is a difference of 2048 bytes. These boards use the same controller so I should expect the same figures here.
Is this just that IDE is not calculating the bootloader for the UNO ? Any idea on this ?

What version are you running? I have 1.0.5 and the boards.txt file has the following values:

uno.name=Arduino Uno
uno.upload.maximum_size=32256
uno.bootloader.file=optiboot_atmega328.hex

pro5v328.name=Arduino Pro or Pro Mini (5V, 16 MHz) w/ ATmega328
pro5v328.upload.maximum_size=30720
pro5v328.bootloader.file=ATmegaBOOT_168_atmega328.hex

You can see that the Pro Mini uses the older, larger, bootloader so it has less available upload memory.

I’m running 1.0.5 also and looked at the board.txt file, same values as you described. So that’s explanes the difference in free memory. Thanks for explaining this.
It’s no problem for me, my sketch is < 10.000 bytes so fits in the UNO and Mini Pro. I can image someone who is programming close to the max memory on an UNO gets a surprise if the sketch ported to a Mini Pro.

Keep in mind that "Free Memory" in this case refers to PROGMEM or Flash. It does not refer to RAM.