Solid wood typically comes in 5/8 to ¾ inches thick; which lends itself to being refinished and sanded many times. There are some drawbacks, and one it that with changes in humidity it contracts and expands and therefore not recommended for any below grade rooms, such as a basement. Engineered is also real wood, but it is not solid. It has a top layer of real wood that is adhered, via glue to, several crisscrossed layers of typical plywood that make it dimensionally stable. What this means to you, is that it is a great option to put in a basement, if you want real wood.
With both types of flooring, the hardwood must sit in the room it will be installed in and get acclimated to that room's temperature prior to installation. Be sure to read the manufacturers recommended number of days for the brands you buy.
Better yet, come into our showroom in Salem, OR and we will walk you through all the specifications of each floor you are interested in. We can help you find the perfect wood floor, whether engineered or solid that will suit your lifestyle and your budget.