What are the differences between BL and BX in ARM assembly instructions?

$BL$ is a directive, is a basic but commonly used means of implementing subroutine. $Bx$ is a basic but commonly used means of implementing functions $BL$ is a directive, is a basic but commonly used means for calls subroutine invocation. $Bx$ is used to return from the subroutine.

$Bx$ is a directive, is a basic but commonly used means of implementing subroutine invocation. $BL$ is a return from the subroutine.

$BL$ is a directive, is a basic but commonly used means of implementing program. $Bx$ is commonly used means of implementing process.

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