There are quite a few words that are formed with down/ up either preceding the actual rootword, or as a particle making for a phrasal verb. But does it change the meaning in any way or carry different connotations? Play down - downplay Scale down- downscale
Interesting question, my suggestion is always to check a good dictionary first, there may be differences in usages and/or meaning, case by case:
In the example you make:
play down and donwplay have similar meaning and usages:
as in the case of scale down or downscale:
If you scale down something, you make it smaller in size, amount, or extent than it used to be.
- One factory has had to scale down its workforce from six hundred to only six.
to donwscale: reduce (something) in size, amount, extent, cost, etc.; downsize
- We want to downscale and buy a smaller house.