The 8871, 9554 btu one ie the rated capacity is the (nominal) btu
The one with (lowest-highest btu range) is the operating range - where the highest figure here is what we refer to as "turbo" mode or essentially redlining the AC for fastest possible cooling.

Usually for comparison we'll see the nominal btu as running the aircon on turbo mode 24/7 does wear out the components (compressor, IDU blower motor) prematurely (also this is why mfg put a countdown timer so the max on turbo is around 20-30mins then it will switch back to normal mode).
Most welcome, not a bro, actually not in the HVAC line myself but I do have friends working in/worked before in OYL, Danfoss, cold chain logistics, solar powered aircon systems with the solar panels and the like.
In the past I used to sell sensors and inverters for industry/production lines. There one needs to pore over spec sheets a lot to propose something usable for "like for like" replacements (especially for sensors).

(1.0HP)
MSY-JS10VF 8,871 nominal / 9,212 turbo btu  / 920W rated power  :confused:
MSY-JS10VF2 9,554 nominal / 9,895 turbo btu / 910W rated power
MSY-GR10VF 9,554 nominal / 11601 turbo btu / 770W rated power

There seems to be two model of 1.0hp JS series - MSY-JS10VF and MSY-JS10VF2 https://www.mitsubishielectricmalaysia.com/...ochure-bpzw.pdf

https://www.mitsubishielectricmalaysia.com/...ochure-bpzw.pdf
Comparing with Hitachi RAS-XH10CKM BTU/h : 9,210(3,070-11,260)
nominal 9210
turbo 11260
800W rated power

Comparing with Sharp AHX9VED2 9700 (3070 - 10000)
nominal 9700
turbo 10000
890W rated power

The Mitsu GR can buy, the JS seems to be almost redline already even in normal mode.
JS without VF2, nominal btu looks underpowered. It will work but cooling may take longer if your room is large. If the room after putting a bed no space to walk around then still OK.
MSY-JS10VF2 with VF2 looks more correct.