Hey emma! I'm not too familiar with anything totally new,
but I'd have a tough time choosing between those two companies.
I'll explain what I see as differences.
I'm a Boss fan, having three micro-digital, half-rack effects that I use for electric guitar.
I see Boss as cutting edge inventions of a very high quality, precision and looks.
Okay, I see I'm typing Boss, but it's Roland Boss.
Roland is the same with keyboards and synthesizers, and aren't super expensive.
Yamaha makes more of a dent in the market with band instruments for high schools,
and while they make quality musical products of all different kinds, they are more utilitarian in design.
While their electric guitars are solid, they don't have a lot of flair, not used much onstage.
I'd still want to just sit with one and play it, to feel the action.
If it's not an acoustic piano, the weighted plastic keys will be different between two manufacturers.
The Japanese people have been very diligent, rebuilding their country and economy after WW11,
and most of what got them overseas was innovative and quality electronics.
Choosing between Roland and Yamaha shows nice support during this time of tsunamic devastation.
I recommend Yamaha piaggero NP 11: it is portable, nice, several sounds, midi and have best touch response than models including SPR. Besides is not very expensive given its quality (I bought it at $ 150)