While Scala's objects may be comparable to OCaml's modules, implicits add something on top of that to bring it much closer to type classes. As the name implies

While Scala's objects may be comparable to OCaml's modules, implicits add something on top of that to bring it much closer to type classes. As the name implies you do not have to specify the instance at each call site. The implicits mechanism can automatically resolve an instance based on the type. If you want a different one you can pass a different instance manually, however.