Other answers have stated the same thing in the same technical terms which might be meaningless in this instance. There is also a practical approach.

Summary:

1. Zoom lens is the general term used for any lens that varies its focal length.
2. Telephoto lenses are lenses that usually have a very high focal length to capture far away objects.
3. A lens can either be zoom or telephoto, both, or neither.
4. Zoom exists in almost all cameras while telephoto lenses are used mainly in professional photography and other high end applications.

Other answers have stated the same thing in the same technical terms which might be meaningless in this instance. There is also a practical approach.

1. Zoom lens is the general term used for any lens that varies its focal length.
2. Telephoto lenses are lenses that usually have a very high focal length to capture far away objects.
3. A lens can either be zoom or telephoto, both, or neither.
4. Zoom exists in almost all cameras while telephoto lenses are used mainly in professional photography and other high end applications.

I think THIS is more like the answer the OP wants. All of you have stated the same thing in the same technical terms which might be meaningless in this instance.

From Difference Between:

Summary:

1. Zoom lens is the general term used for any lens that varies its focal length
2. Telephoto lenses are lenses that usually have a very high focal length to capture far away objects
3. A lens can either be zoom or telephoto, or both, or neither
4. Zoom exists in almost all cameras while telephoto lenses are used mainly in professional photography and other high end applications

Other answers have stated the same thing in the same technical terms which might be meaningless in this instance. There is also a practical approach.

Summary:

1. Zoom lens is the general term used for any lens that varies its focal length.
2. Telephoto lenses are lenses that usually have a very high focal length to capture far away objects.
3. A lens can either be zoom or telephoto, both, or neither.
4. Zoom exists in almost all cameras while telephoto lenses are used mainly in professional photography and other high end applications.