Earbuds a is using a newer version of Bluetooth that might use less power, but in general. Different models aren’t directly comparable by the mAh rating. Some earbuds might have speakers and amplifiers that use more power, while others might be more efficient. If you like earbuds b more then stick with those

Both are same brand , B model is just higher battery capacity, but i believe A case charger is faster? Another benefit from A model that it has a slightly louder mic and volume from a test call, although both should be the same 9mm driver

Yes earbuds A case should charge them faster as it has a much higher output combined with a smaller battery. If you can’t hear much of a difference between both of them music wise then it should be either the same or a similar driver

Hey, sometimes TWS earbuds using the newer (Qualcomm/Airoha/etc.) chipsets are opting for the more powerful ones (the new chipset are usually more efficient with the battery life, so it's just the manufacturers opting to have better performance instead of battery life) and so this can drain the battery more.

Oh and make sure they're using the same codec. Usually LDAC will drain the battery a lot (and add more latency), and so you can just use AptX Adaptive or regular AptX as not a lot of people can tell the differences.

Check Scarbir's website, regancipher's Head-Fi and Youtube reviews, /r/Earbuds, etc. for the new budget TWS earbuds or best value.

Info about UTWS3/5 battery life (5-7 hours) and also TWS earbuds volume variability: https://www.reddit.com/r/headphones/comments/10yr7js/finaly_good_audio_on_the_go_utws5_and_fh5s/j803bbw/

Latency with TWS earbuds, TWS adapters, Bluetooth 5.3 LC3 tech, et cetera: https://www.reddit.com/r/HeadphoneAdvice/comments/11pa48l/wireless_gaming_earbuds_for_pc_gaming/jbx09oi/

Wired IEMs with TWS adapters (like FiiO UTWS3/5, KZ AZ09 Pro, etc.): https://www.reddit.com/r/HeadphoneAdvice/comments/125a33h/upgrading_my_xm4s_wireless_iem_advice/je3kulz/

fast charging is a make up for low battery ? worth ? yes the one with low battery is a bit higher on volume and mic , i added models to the thread

my earbuds are from HTC, they're authentic and as a call quality vs noise, it beat soundpeats free2classic and belkin soundform play , but as for volume htc is below them , anyways i added the models in ,y thread, and i bought both of them to test out and the summary is what i listed in the thread, both are acceptable, so it's either 5.3 with fast charging , a bit louder and lower battery , or 5.1 with huge battery but without fast charging and a bit lower audio, or return both and risk with new experiment lol