With the upcoming hard fork of Bitcoin to its SegWit2X counterpart, there are two distinct differences between the fork (SegWit2X), and Bitcoin. These two distinct differences being, the implementation of Segregated Witness (SegWit), as well as an increase in block size from 1 MB to 2 MB.
Segregated Witness (SegWit), is one of a plethora of solutions that was proposed in-order to help solve Bitcoin’s scaling issue. SegWit works by moving signature data in a transaction into an extended block. By transferring this signature data to the extended block, space is freed up in the main block, which therefore allows for more transactions to be included in it.
Even though SegWit has successfully been activated on the Bitcoin network, SegWit transactions currently only make up about 11.5% of all transaction that occur on the Bitcoin network. Wallets still need to be upgraded in-order to support SegWit, which is hoped will help encourage wider use of SegWit based transactions.
2X is a term that refers to the block size limit. A two time increase of the current Bitcoin block size limit of 1 MB, to give a new block size limit of 2 MB. The block size limit is a contentious issue because of the detrimental effect it is currently having on the Bitcoin network. As transaction volume increases on the Bitcoin network, the current block size limit of 1 MB has proven to be ineffective, as is shown by the resulting slowdown in the network.
A simple solution that has been proposed is to simply multiply the current block size limit by 2, that is, increase the block size limit from 1 MB to 2 MB. However, there are worries that increasing the block size limit would lead to the centralization of Bitcoin. An increase in the block size may result in nodes on the Bitcoin network being more expensive to run. Therefore, fewer people would be unable to operate a full node, making Bitcoin more centralized.
The common ground that exists between Bitcoin and SegWit2X is that they are both attempting to solve Bitcoin’s scaling issue. However, both approach this problem in different ways. SegWit2X approaches this problem by: Implementing SegWit and increasing the block size limit from 1 MB to 2 MB.