Although they both play critical and related roles in cryptocurrency transactions, public keys and private keys each have a distinct function.
Private keys
Designed primarily to prevent theft, a private key works in conjunction with a public key (address) to allow a designated user to send or receive coins or tokens. Specifically, the user will require their own private key, which is known only to them, to withdraw such coins or tokens from their own public address. Alphanumeric characters are the typical form of private keys, thus adding an additional level of security and a reduced risk of unauthorized access.
Public keys
A public key, which is created automatically with a private key by a first-time user of the venues of bitcoin or altcoins, are automatically condensed to create the user’s public address. As its name suggests, the public address is intended to be made available as needed at the discretion of the user, to enable the transfer of cryptocurrency.
Thus, it is fair to say that although they are not identical, in the world of cryptocurrency public keys and private keys cannot function without each other.