Question about vintage power cable/psu for old amp

[philv]

I am looking at a 70s amp.

Tnere are 2 versions.

One with a fixed cable
With 210w written on the back of the amp.

The other with removable/kettle lead cable
With 300w written on the back of the amp.

The seller mentioned something about it having a cold device connection.
I didn’t understand.

Both versions are 25 wpc.

Has one got a bigger/better psu?

Thanks for any explanation.