Wifi Signal booster or expander -difference
 

My home is three levels, the internet router was placed in the second floor where most of the entertainment is located. However the outlying rooms, downstairs (furthest from the router) and the den on the third floor (furthest corner from the router (room two floors above the bedroom with the problem)), the wifi signal is really weak.

I have been researching wifi bi-directional Wi-Fi signal amplifier (boosters) and / or Wi-Fi repeater (range expanders)

After all the geek speak, I end up not understanding which is better or how to choose between them.

Can somebody simply explain the difference and which is more cost effective. What the pros and cons are for each?

Two names for the same thing, as far as I can tell.

Each repeater/booster/whatever you want to call it will halve the available bandwidth. Far better to put in a separate access point that is hard wired to your main router, either via ethernet cable or powerline ethernet.