I recently installed Mate 15.04 from the image.
I ran fdisk and noted:-
/dev/mmcblk0p1 * 2048 133119 131072 64M c W95 FAT32 (LBA)
On Raspbian the boot partition is
/dev/mmcblk0p1 8192 122879 57344 c W95 FAT32 (LBA)
From what I had read in the past, the start of the partition is aligned on an 8k boundary, rather than the normal, even though this wastes a few k to ensure efficient use of the blocks on a SD card.
Is there a reason this has not been done for Ubuntu?