For Honda in general a change in last three characters in the part number mean a minor change in the part or change in the vendor supply chain.
The new part number supersedes the previous part number. A part that is superseded, in this case the D01 filter, can and will continue to be used until all the inventory is sold and for our purposes is completely interchangeable with the D02 filter.
On the Honda car side this occurs with PLM-15400-A01 and PLM-15400-A02 oil filters. The latter superseded the A01 filter nearly 10 years ago and since the 02 has a plastic bypass valve and the 01 a metal bypass valve the internet expert filter "cutter-openers" on oil forums early on proclaimed the 02 as a cheap replacement and to avoid it at all costs if you didn't want your Honda engine to immediately explode. However Honda had inventory of the 01s for a long time before the 02s pretty much became all you could get. This thought process doesn't give Honda room to change designs and/or suppliers over time when they believe a revision doesn't affect service or performance. Contracts are often let to the lowest cost supplier but Honda has high standards that the lowest cost suppliers have to meet. That's quality in a nutshell. It only has to be good enough to meet the standard and Honda has high standards.
I'm sure that soon there will be a sentiment like that in motorcycle forums and the D01 will be elevated to desirable if not collectable status while the D02 will be junk to be avoided.
motorcycleinfo.calsci.com
