I would suggest to stop reading into the names of the cards and stress the importance of understanding and focusing on their ratings.
First of all:
MB = Megabyte
Mb = Megabit
Mbps = MegaBITS per second
MBps = MegaBYTES per second
MB/s = MegaBYTES per second
There are 8 Megabits in a Megabyte.
UHS = Ultra High Speed bus. It has 3 classes, and most cards you see will be UHS-I depicted by the roman numeral "1" on the card. Class 1 (I) is more than enough.
UHS Class = This is where you see the number inside the "U". What you want is a UHS-1 Class 3 (U3) card. Think of it as a sub-class of the UHS rating. The number denotes the minimum sustained write speed (i.e. U3 = 30MB/s)
V = Video Speed Class. The number following the V corresponds to the minimum sustained write speed (i.e. V30 is 30MB/s, V60 is 60MB/s and so on).
A = a designation for minimum sustained write speed AND minimum read/write IOPS.
A1 is fine for the Mavic Air provided it is also a V30/U3 card. Don't worry about this one too much.
The only thing that really matters for video recording is minimum sustained write speed, which is not advertised explicitly. Everyone always looks at maximum transfer/read speed which is what the manufactures are quick to advertise, but means nothing for this application.
For the Mavic Air, you need a card that has a minimum sustained write speed of at least 12.5 MB/s (100Mbps), and having a buffer there for momentary drops in write speed is also important. You cannot look at maximum advertised transfer speed and infer anything from that.
Class 10 / V10 /U1 cards are not fast enough - they only guarantee sustained write speeds of 10 MB/s.
You need V30 / U3 cards which guarantee a sustained write speed of 30MB/s (240Mbps) which is more than enough to cover the Mavic Air in 4K/30.
Once you understand the ratings, you will never have memory card speed issues again unless the card itself is defective.
These cards are my go-to:
SanDisk 64GB Extreme UHS-I microSDXC Memory SDSQXAF-064G-GN6MA