Rijndael can use different block sizes, but AES uses a fixed block size of 128-bits.
So for AES, the block size must always be 128-bits!!!
Key Size Block Size
128 128 192 128 256 128
Basic Information
Official NIST standard
Won first place out of 15 other AES contestants
Pronounced “Rhine Dall”
Named after its developers Vincent Rijmen and Joan Daemen
Rijndael is the actual name of the algorithm, AES is the standard
Symmetric block cipher
Proved to have the best security, speed, and scalability
Stronger than DES and 3DES
Supports 128, 192, 256-bit keys
Can be used by the government to protect sensitive but unclassified data as well as secret and top secret
Rijndael allows the use of block size same as key size.