The $150M was basically a settlement because Apple was threatening a multi-billion dollar lawsuit over the theft (and it was blatant, the code was definitely a copy).
In addition, MS had to support Apple, writing Office etc. for MacOS for the next 5 years.
Apple said that in return they'd drop the look-and-feel lawsuits that everyone said were going nowhere. That gave it more a semblance of a "deal" than a "MS screwed up bigtime, got caught, and are paying for it now".