No, there is no difference. Any partitions created by Vista / 7 will be easily accessable from XP.
This is not quite true. There are actually differences between NTFS used in different Windows versions, as described in this Wikipedia page.
For the most part, you can use NTFS volumes in a dual-boot system under XP and Windows 7, but there can be some issues with some of the more esoteric stuff. For example, XP can only deal with one System Restore point. If you mount a Windows 7 or Vista volume with multiple restore points, XP sees them as invalid and deletes all of them. Therefore you should avoid using an NTFS volume with XP if you are depending on restoring to a previous version.
@Zoron: wrong. Windows XP will be able to do whatever it wants on a 7-formatted NTFS volume. In fact, even Windows 2000 can.
@sminlal: you are right, but vague.
To be more precise: Windows XP, Vista and 7 all use NTFS version 3.1. However, NTFS 3.1 is a highly complex and advanced file system, and in fact its design includes features that not all versions of Windows can support. So, there is no chance of Windows XP corrupting a Windows 7 volume (making all data impossible to access), however XP may destroy data that Windows 7 saved to disk, if said data is 7-specific (alternate data streams not copied, etc.)
If you're using NTFS for file storage, fear not: it'll work, you won't lose data, the volume won't be corrupted. I'd recommend against forcing the install of both Windows XP and Seven on the same partition, though (7 will create a 100 Mb boot partition for essential files; I'd recommend against touching it).
Uhh.. that's what I said. Windows XP can read and write to Vista / 7 partitions seemlessly. I said that Windows XP would not recognize Vista or 7's bootloaders... and that is true. If you try to install XP after Vista or 7, XP will overwrite their bootloaders with it's own.
I did make a mistake in saying that NTFS is exactly the same across all versions of Windows; I should have said in terms of creating / formatting and using partitions, you won't notice a difference between XP / Vista / 7. I never said that XP wasn't able to do "whatever it wants" on a 7-formatted NTFS volume... I just pointed out it wouldn't like the bootloader.
XP may destroy data that Windows 7 saved to disk, if said data is 7-specific (alternate data streams not copied, etc.)
Actually alternate data streams have been in NTFS right from the first version and all NT-derived versions of Windows support them. The way people usually loose alternate data streams is by copying files that contain them onto a FAT volume, since FAT doesn't support them.