Confused with RAM part numbers, voltages and compatibility

Kilobyte Kid

Confused with RAM part numbers, voltages and compatibility

Hello!

I am trying to help a friend upgrade (to 2x4GB) the memory of his 2x2GB MacBook Pro 15-inch, Mid 2010   |   2.4GHz Intel Core i5   |   MC371LL/A   |   MacBookPro6,2

 

I recently upgraded my Late 2008 13" Unibody MacBook with 2x4GB Crucial kit I purchased from a big online webstore in the UK - Kit model number CT2C4G3S1067MCEU and invididual modules part number CT4G3S1067M.C16FKR (1.5V). (My notebook officially only supports 4GB, but it works great with that RAM and Boot ROM Version MB51.007D.B03 & MacOS X 10.6+)

Now, I tested those same Crucial memory modules from my notebook in my friend's MacBook Pro and they worked flawlessly. So I headed to the same big online store to order another kit (same one), but it is temporarily out of stock, so here I am (I thought you only ship to the US, that's why I ordered from another site in the first place). 

 

I first checked the US site (my browser defaulted me there). Tried searching for the MacBook Pro and strangely enough there are 2 options for the same system in the drop-down menu: MacBook Pro (15-inch, Mid 2010) and MacBook Pro 2.4GHz Intel Core i5 (15-inch DDR3) MC371LL/A. 
Now, both produce different external numbers for the single 4GB and 2x4GB kits - CT3309362 / CT3309361 and CT3309018 / CT3309058 respectively. But both the 4GB modules cross-check to CT4G3S1067M and the 2x4GB kit to CT2K4G3S1067M


I then saw the EU option and switched to that. Ran the same search and again got different external numbers:
MacBook Pro (15-inch, Mid 2010)  - CT3327570 / CT3309360
MacBook Pro 2.4GHz Intel Core i5 (15-inch DDR3) MC371LL/A - CT3327547 / CT3309098
Again they both cross-check to CT4G3S1067MCEU / CT2C4G3S1067MCEU (my kit)

So, here is what I don't get: I can order CT2K4G3S1067M from the US (through a friend who is visiting me from the States next week) or CT2C4G3S1067MCEU from the EU store. 

However, what I don't understand is why the US site lists the modules as 1.35V and the EU site as 1.50V. Why the difference?

And one more question - I can also get 2 x CT51264BC1067.M16FD modules from another friend's older iMac. Would these work on my friend's MacBook Pro 15-inch, Mid 2010 or my Late 2008 13" Unibody MacBook? They were previously used in iMac (21.5 and 27-inch, Late 2009) iMac10,1 and both CT2C4G3S1067MCEU and CT2K4G3S1067M are now shown as compatible for it when checking, so I guess the older modules should, in theory, be very similar. Am I right?

Thank you and excuse the long post!