This is definitely a tick. If it were a spider it would appear that the legs all come from a central point, as spider bodies are separated into segments, whereas tick bodies are not.
There are two main types of ticks - hard ticks and soft ticks. They look quite different. Hard ticks have what's known as a scutum (translates to shield) that covers the front half of the animal, while soft ticks lack the scutum. This one is a hard tick.
More specifically what you have here is, most likely, a male American dog tick (Dermacentor variabilis). I say this because of the pattern on the scutum and the leg color, other similar species have different color legs.