VMPL and MRPL

[Chinni18]

I am rather confused in the difference between VMP and MRP of labour.
Which one do we use as the firm's demand curve for labour?
In problems solved so far, we've generally equated MRP to wage to obtain labour demand.
Am I right in thinking that MRP is for perfect competition and VMP for monopsony?
I'd be really grateful if someone could clarify this.

[aditi5000]

MRP = MR * MPL

demand for labour depends on which type of competition in two markets - output and labour. for Pc in both output and labour market for example, labour gets paid wage = vmp
for monopoly they get wage = mrpl

[Chinni18]

Ohh.. So it's rather like equating P=MC in pc and MC=MR in monopoly.. Acha. Thanks aditi

[aditi5000]