The colour of the name field indicates the signing power of the signatory:

Black on light grey:
right to sign single without any amount limit and no other limited power and no instruction

White on red:
signatory with no rights at all or company rubber stamp

Black on yellow:
variant signature

White on blue:
signatory with right to sign collectively or as part of a group, with or without amount and time limits (in fact, any other right to sign not covered by the white, yellow, or red background colour)