SOL under $15 ?, page-20

They are certainly very similar however not quite the same.

BKW has three main "pillars" from which it earns money. Its building product division (for which is is best known) along with a large industrial property trust and the SOL investment (via dividends)

SOL is an investment conglomerate with stakes of various sizes in a variety of different companies operating in different sectors. BKW is the third largest stake (in terms of market value) in the SOL portfolio behind TPG and NHC

This does make it kind of hard for a retail investor (e.g all of us on this forum) to discern which of the two is a better option (and realistically you cant go too far wrong with either). The two also have periods when the share price tracks the same and others when one might drift behind the other (BKW has drifted behind SOL in recent times). There is a bit of a difference in dividend yield at the moment meaning that BKW is returning a little better and I would also say that BKW is obviously more exposed to one cyclical industry (e.g the housing market) than SOL (although being a lot more stable than your traditional building products company).

I hope this helps