Is there a difference between voltage divider and attenuator?
The attenuators that your picture show are designed for the use with certain coaxial cables. These cables have a special wave-impedance (e.g. 50 ohm) which describes the relation of the H- and E-field of the electromagnetic wave that propagates in the dielectric of the cable. If your attenuator has an input impedance that differs from the wave-impedance, part of the energy of the wave will be reflected back to the signal source. That's why you have to use those special attenuators for high-frequency signals on a coaxial cable.

So yes, your suggestions are basically correct. In case of high-frequency signals a simple voltage divider with arbitrary resistors will not do the job quite well. In case of DC there is no difference.