AES vs 3DES
AES (Advanced Encryption Standard) and 3DES, or also known as Triple DES (Data Encryption Standard) are two of the current standards in data encryption. While AES is a totally new encryption that uses the substitution-permutation network, 3DES is just an adaptation to the older DES encryption that relied on the balanced Feistel network. Basically, 3DES is just DES applied three times to the information that is being encrypted.
AES uses three common encryption key lengths, 128, 192, and 256 bits. When it comes to 3DES the encryption key is still limited to 56 bits as dictated by the DES standard. But since it is applied three times, the implementer can choose to have 3 discrete 56 bit keys, or 2 identical and 1 discrete, or even three identical keys. This means that 3DES can have encryption key lengths of 168, 112, or 56 bit encryption key lengths respectively. But due to certain vulnerabilities when reapplying the same encryption thrice, using 168 bits has a reduced security equivalent to 112 bits and using 112 bits has a reduced security equivalent to 80 bits.
3DES also uses the same block length of 64 bits, half the size that of AES at 128 bits. Using AES provides additional insurance that it is harder to sniff leaked data from identical blocks. When using 3DES, the user needs to switch encryption keys every 32GB of data transfer to minimize the possibility of leaks; identical to when using the standard DES encryption.
Lastly, repeating the same process three times does take some time. With all things held constant, AES is much faster compared to 3DES. This line gets blurred when you include software, hardware, and the complexity of hardware design to the mix. So if you have 3DES accelerated hardware, migrating to AES implemented by software alone may result in slower processing times. In this aspect, there is not better solution than to test each one and measure their speed. But when it comes to security, AES is the sure winner as it is still considered unbreakable in practical use.
Summary:
3DES uses identical encryption to DES while AES uses a totally different one
3DES has shorter and weaker encryption keys compared to AES
3DES uses repeating encryption keys while AES does not
3DES also uses a shorter block length compared to AES
3DES encryption takes longer than AES encryption