according to my friend:

800 has 3 useful selectivity choices, the 150 has limited choices
800 has a selectable sideband sync that can be used with a 6KHz
filter, the 150 uses only the 2.5 filter
the 800 has a bass and treble, 150 none
800 has fast and slow AGC, the 150 none
the 800 has a keypad with up and down buttons, the 150 has none
the 800 sounds better
the 800 has more memories
the 800 has better performance
the 800 can be bought for less than $300, he got his for $280 including
shipping, the 150 cost over $400

he sold his 150