These two are different products and usually used for different purposes. Spotting scopes are usually preferred for bird watching, stargazing and hunting during the daytime. High-end binoculars, on the other hand, can be used for various tasks that vary in nature. Low-end spotting scopes are not good for astronomy or vigorous outdoor activities as compared to high-end binoculars. This is because they are less rugged, waterproof, and compact. Most of them are fragile and delicate and sometimes not waterproof.
Unlike spotting scopes binoculars are not very good for planetary viewing. They are more suited for clusters and similar objects like the Pleiades, Trapezium and the double cluster. They are also very good for viewing the night sky as compared to low-end spotting scopes since the lighting is usually an issue when it comes to low-end spotting scopes.
Spotting scopes have larger apertures than binoculars meaning that they offer clearer images that are sharper and brighter from a further distance. This enables hunters to identify their prey faster. They are a little bulky and difficult to carry around. They also require additional props like tripod stands and take a little longer to focus as compared to binoculars. If you are on the move it is advised that you become patient when using spotting scopes and this can be a little annoying to hunters.
Binoculars on the other hand, are basically a couple of mini telescopes that have been joined together. They usually need the users to apply both of their eyes, unlike spotting scopes which require the user to use a single eye. They are mostly handheld for convenience and come with a cord that can be slug across the neck very fast. They are usually very portable and weigh less than spotting scopes. The need no installation and it is not necessary to use tripods with them. They are not very good when it comes to viewing objects from a long distance away since they have a lower magnification power and the viewer will need to get closer. For birders who like observing the intricate details of birds, the best device would be a spotting scope.
Therefore it comes down to the purpose a viewer intends to use these devices. If the activity requires long distance viewing capability on a stationary location then a cheap spotting scope would be ideal but if the activities require quick movement and short-range viewing then a pair of high-end binoculars would be more than enough.