GPT (GUID Partition Table) and MBR (Master Boot Record) are two different partitioning schemes for hard drives.
MBR is an older partitioning scheme that was introduced in the 1980s. It uses a 32-bit partition table to define the partition layout on the disk. MBR is limited to four primary partitions, or three primary partitions and one extended partition. An extended partition can then be divided into multiple logical partitions. MBR has a maximum disk size of 2 terabytes (TB).
On the other hand, GPT is a newer partitioning scheme that was introduced in the late 1990s. It uses a 64-bit partition table, which allows for more partitions and larger disk sizes. GPT can support up to 128 partitions, and its maximum disk size is 9.4 zettabytes (ZB), which is virtually unlimited for the foreseeable future. GPT also includes a backup partition table to help prevent partition table corruption.
Another difference between GPT and MBR is that GPT includes a unique disk identifier, whereas MBR does not. This identifier can be used to identify a specific disk, even if it is moved to a different system.
In summary, the main differences between GPT and MBR are the maximum disk size, number of partitions, and the size of the partition table used. GPT is the newer and more flexible partitioning scheme, whereas MBR is the older and more limited partitioning scheme.