There are substantial differences and similarities between routers and shapers.
The similarities are with function and the differences are in performance.
Both tools are stationary and the operator moves the work, not the tool.
Both use fences, collars or bearings to control the path of the work.
Shapers – Power and Production
Shapers are essentially for edge or end cuttings.
They are cabinet shop and millwork tools, and as such are heavy handed, heavy duty and heavy weight.
They are designed for all-day door, drawer or molding operations. Duty cycles are measured in “shifts” not minutes. They are production animals.
Their cutters are big (way over 2″ in diameter), expensive and last for hours.
The set ups are not particularly difficult but once in “spec” they are not touched for the length of run.
Although capable of experimental work, shapers are usually set up for routine big jobs of long duration.
Shapers spin slower than routers, usually in the 7-14,000 rpm area and their power demand starts where routers leave off, (around 3 HP).
Router tables are welter weights by comparison. It takes two routers to equal one shaper.
Routers – Inexpensive Versatility
Router tables give up production for versatility.
In my view, the router table not only performs edge, face, and end cuttings. In addition, inside work is also possible.
Dados, mortises, and other blind inside excavations are not possible with shapers, nor are dovetails, a distinct advantage for the router table.
Router bits for all sorts of woodworking are common and there are probably more router bits than shaper cutters except for door, drawer and window applications.
The router is an offshoot of the shaper, not a substitute for one.
Its price range is well within the reach of most woodworkers; shapers of any nobility start at $1500.
You can make a router table in a weekend; the shaper is a factory product made with many sophisticated assemblies.
Router tables are easy to fixture, and they fill an important need for a wide range of cabinet and furniture responsibilities.
They are great for short run solutions but don’t expect shaper performance from one.