why my hardisk is invisible in w7?

[toqeer]

1-i installed window vista and window7 too. but when i open the window7 the drive in which vista is installed is not visible but when i open vista then i see the drive in which w7. i dont know why?
will it is due to formate of disk?
2-tell me difference between fat, fat32, ntfs type?

[Liverpool_fan]

Windows?
Open Computer Management. Then Disk Management and assign drive letter to Vista partition.