When talking about projector screens you got two main categories, the fixed installation and portable screens. Which one you need will depend on your requirements for its use, The fixed installation screens are those that you set up permanently, there are 3 also known as fixed frame, pulldown and tensioned installation. These screens are perfect for specific rooms where the screen will not be retracted when not used. If you need a screen at home to watch movies or TV shows only in a specific room then a fixed installation is your best option.
The portable screens are perfect for rooms where a flat screen cannot be placed permanently, small rooms, offices, business, conference rooms etc. If you need a screen for a business room where you need to set up a scenario for a special occasion then the portable screen will be the best way to go.
When talking about aspect ratio there are several variations (4:3, 16:9, 2.35:1) these options allow you to change the resolution in order to find the best source. The aspect ratio refers to the space between its with and height meaning that a 4:3 ratio will display a more square image perfect for TV shows, meanwhile a 16:9 ratio will display a more rectangular image, perfect for standard movies.
Most of projectors come in a standard presentation of 4:3 aspect ratio, however a many of the new brands have been moving forward from 4:3 in recent models, this means that if your PC or laptop has a widescreen display a 16:9 or 16:10 aspect ratio will display better resolution being the best option for you.