Understanding the Linux Kernel says
The first block in each Ext2 partition is never managed by the Ext2 filesystem, because it is reserved for the partition boot sector.
As far as I heard, a block and a sector are not the same concept on a hard drive. A block usually consists of a number of sectors.
The first block in a partition is called a boot block. It is not a sector, so not called a boot sector.
The first sector in a disk is MBR, which is a sector not a block.
Is my understanding correct? How shall I understand their usages in the quote?