Well spotted. I guess that, and the incorrect footer for page 1, both slipped through the net when copying and updating the datasheet some 9 years ago !There appears to be a conflict of the titles on that page.
IIRC, the main difference was the provision for a breakout strip of pins between the PICAXE and the ULN2803. This allowed the PICAXE outputs to be accessed directly, rather than the ULN2803's low side switching. When I purchased mine from a local supplier several years ago, I must have got old stock and ended up with a CHI30 (or 30A?), without the breakout pads .I have to admit I cannot recall what the differences are between a CHI030A and CHI030B. The circuits seem exactly the same, the datasheets seem the same except for a few tidying-up edits but I didn't read either in full.