What is the difference between an electronic and a digital signature?

Different electronic signatures.

Electronic signatures

In South Africa, any mark made on an electronic document with the intention to serve as a signature is considered an electronic signature. Although electronic signatures are legal signatures, electronic signatures are not protected with cryptography and is considered low trust signatures.

Digital signatures

To protect the document signer and the integrity of the document, use digital signatures. Digital Signatures use Public Key Cryptography to protect the integrity of the document and tie the identity of the signer to the digital signature.
A digital certificate belonging to the signer is embedded into the document at the time of signing.

Advanced Electronic Signatures

Advanced Electronic Signatures are a subset of electronic signatures governed by the South African ECT Act and are considered the highest trust digital signatures.
Only the South African Accreditation Authority (SAAA) accredited vendors can issue Advanced Electronic Signatures.

For a full discussion see the LAWtrust article: Wet signature vs. Electronic Signature vs. Digital Signature.