The key difference between asymmetric and symmetric encryption is that symmetric encryption uses one secret key that has to be shared among the sender and recipient of the message, while asymmetric encryption utilizes a private key and a public key to decrypt and encrypt messages during communication. Asymmetric encryption is a relatively new technique compared to symmetric encryption.
A major shortcoming of symmetric encryption is that security is entirely dependent on how well the sender and receiver protect the encryption key. If the key is jeopardized, intruders can decrypt and gain access to all messages encrypted with the key. Asymmetric encryption is more secure because it relies on digital certificates. Both the private and public keys are related, but cannot be derived from each other. If either of the keys is compromised, the intruder cannot use it find the other key.