This question is in relation to Wikipedia article on Format Preserving Encryption
It says the following
It is also possible to make a FPE algorithm using a Feistel network. A Feistel network needs a source of pseudo-random values for the sub-keys for each round, and the output of the AES algorithm can be used as these pseudo-random values.
However I was taking a look at an implementation of FPE (Botan Crypto library). It is based on the scheme FE1 from the paper "Format-Preserving Encryption" by Bellare, Rogaway, et al
In the implementation I think it is using the SHA-256 hash to generate the pseudo-random values.
How does this compare (with respect to security) to the alternative of using the AES algorithm to generate the pseudo-random values?
Are both equally valid methods?