Pop piano is playing pop on the piano itself. Portable keyboard refers to the keyboard with auto-accompaniment (ie PSR keyboards). Playing style is different. Pop piano plays both hands. Portable keyboard a lot of one-finger chord styles.
It's not abt no one helping u. Firstly, u gotta ask urself what u want to learn and get out of learning? At least, the answer is not "to take lessons at Yamaha". Tell us more
What I know yamaha don't teach too in-depth about pop/jazz music. Actually this happen to all pop school if they have to structure course within in a time period. It is better to block instructor by monthly basis. That less it work for me.