Can you use a smoothie maker as a blender?

Yeah. There are generally two distinct types of smoothie makers, or stick blenders: "soft food" and "hard food". If you got yours at a supermarket for under $30, it's almost certainly for soft food only. That means soups, smoothies and possibly a guacamole. Hard food blenders cost upwards of $60 at minimum and can do ice, carrots and nuts. They're totally brilliant and interchangeable for a blender in most instances. Check your manual.