Double Hung Windows 
Double hung windows are most common and operate vertically.  In other words, double hung windows move up and down.  One sash can slide past the other such that the top and the bottom of the window can be open at the same time which maximizes ventilation.  Although it is possible to have sashes that are not of equal height, most are.  Many homes with original windows have single hung windows which means only the bottom sash operates. 

Three Part Slider
Sometimes referred to as a flat bay window, the three part slider is a less expensive alternative to a bay window.  The center window is fixed (picture window) while the two ends slide inwards towards the center of the window to allow ventilation.  Three part sliders are generally used in openings that are much too wide to make a two part slider that would be strong enough to last.  Design accents are often put in the ends for an added touch.

Bay Windows
Bay windows are magnificent both from the exterior and the interior of a home.  Projecting outward, typically set at 30 or 45 degrees, it opens up any room if a conversion takes place.  The two end windows are functional and a customer can choose between double hung ends or casement ends.  Since this extends off of your home it creates a different look and hence is worthy of its cost, which is more than that of a standard window or a three part slider (flat bay). 

Two Part Slider
Two part slider or slider windows operate horizontally and are typically wider than they are tall.  The two sashes meet in the middle, where the vinyl replacement window locks.  Both sashes operate on all two part slider windows unless the unit is manufactured with a vent opening.  The majority of the slider windows Home Visions replaces are in the home's basement.  

Bow Window
The main feature in a vinyl replacement bow window is that you have 4 or more sections joined together into one unit and are installed like a semi circle or radius from edge to edge of the window.  This is what gives it the name, "bow" window.  They are used in large openings and bow windows maximize lights.  Architecturally, these are very beautiful windows.  Each section can be functional as well.