I find the shiny side of a CD to be informative sometimes. I mostly check it nowadays so I can keep a little notepad entry of which pressing I own. I'm at work at-the-moment, and my bedroom computer (which I would normally remote-desktop to) has crashed, but I keep extra copies of most of my Shiina Ringo rips at work, including any human/software logs I made when I did the rips. According to my notepad entries that I'm insane enough to keep around...
My Mori-pact is
And
my Kame-pact is
Probably means your copies were somehow manufactured earlier than mine, even though I bought mine from the same vendor (CD Japan) before you bought yours. I think the obi also mentions the base TOCT (Toshibi-EMI CD) numbers. Everything beyond the 80 and the 81, are purely pressing-related. Maybe not dramatically different enough of a pressing that you should start calling things "first-press" and "second-press", but it just means they had to produce a new/different CD mold at one point (they lost or retired the previous mold) for basically the same digital master.
MD5s/CRCs are usually different between pressings even if the digital master is the same, because audio CDs are messy like that. But if you have two people with "TOCT-24781 1 C4"s, ripping both of them with the same CD/DVD drive model, or different drive models but with the appropriate Offset Correction, they
will end up with the same MD5s/CRCs as each other.
Sometimes when things are officially called "first" and "second" press, they
mechanically ARE
the same press (with matching MD5s/CRCs), and are different for packaging/marketing purposes only. If we ever start comparing rips (with Offset Correction and checksums), we'd better damn well be clear about the manufacturing mold, rather than focusing on the packaging. Otherwise you have people who are new to Offset Correction, who are thinking that their rip might be wrong, when in fact their rip could be correct
for the pressing they happen to own, but it simply isn't a 100% match of a rip for a different pressing owned by someone else.
I hate audio CDs sometimes. They have too many technical flaws that aren't even involved with the sound quality (and some flaws that
are involved with the sound quality). Microsoft (given the chance) couldn't have screwed up Redbook much more than Sony/Phillips did.