I am going to resize my sda2 NTFS partition. When gathering info with ntfsresize, I get:

ntfsresize --info /dev/sda2

ntfsresize v2013.1.13 (libntfs-3g)
Device name        : /dev/sda2
NTFS volume version: 3.1
Cluster size       : 4096 bytes
Current volume size: 21999993344 bytes (22000 MB)
Current device size: 23622320128 bytes (23623 MB)
Checking filesystem consistency ...
Accounting clusters ...
Space in use       : 10673 MB (48.5%)
Collecting resizing constraints ...
You might resize at 10672590848 bytes or 10673 MB (freeing 11327 MB).
Please make a test run using both the -n and -s options before real resizing!

Can you tell me what is the difference between volume and device size?

As for device size, 23622320128 bytes / 1000^2 = 23622.3 MB. Why is 23623 MB reported instead of 23622?

Note that parted confirms this value:

parted  /dev/sda2 unit MB p
Model: Unknown (unknown)
Disk /dev/sda2: 23622MB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags: 

Number  Start   End      Size     File system  Flags
 1      0.00MB  23622MB  23622MB  ntfs