LX51 vs BL51, AX51 vs A51

[mr_creosote]

Hi,

I just noticed that my PTX and PRX projects use different assemblers and linkers -- not sure why. I got the sample projects from Nordic. What's the difference between LX51 vs BL51, AX51 vs A51? Which should I use?

Best,

Mahesh

[mr_creosote]

thanks!