Wiki is pretty good on this. it says fission waste products have half-lives up in the thousands of years. Fusion waste products are more like 50 to 100.

I guess the nature of neutron activation of containment in a fusion scenario is different to the fission activity inside plutonium, thorium or uranium, and their post processing. Fission reactor inputs have pretty serious chemistry to strip their radioactive elements, concentrate, and store.

I think this may be inherent in the chemistry of the elements needed to fuel a fission reactor.

I'm unable to say if this is accurate, I too would love a better description, and this is the one wiki points to:

https://iopscience.iop.org/article/10.1088/1741-4326/ac62f7

Abstract In the absence of official standards and guidelines for nuclear fusion plants, fusion designers adopted, as far as possible, well-established standards for fission-based nuclear power plants (NPPs). This often implies interpretation and/or extrapolation, due to differences in structures, systems and components, materials, safety mitigation systems, risks, etc. This approach could result in the consideration of overconservative measures that might lead to an increase in cost and complexity with limited or negligible improvements. One important topic is the generation of radioactive waste in fusion power plants. Fusion waste is significantly different to fission NPP waste, i.e. the quantity of fusion waste is much larger. However, it mostly comprises low-level waste (LLW) and intermediate level waste (ILW). Notably, the waste does not contain many long-lived isotopes, mainly tritium and other activation isotopes but no-transuranic elements. An important benefit of fusion employing reduced-activation materials is the lower decay heat removal and rapid radioactivity decay overall. The dominant fusion wastes are primarily composed of structural materials, such as different types of steel, including reduced activation ferritic martensitic steels, such as EUROFER97 and F82H, AISI 316L, bainitic, and JK2LB. The relevant long-lived radioisotopes come from alloying elements, such as niobium, molybdenum, nickel, carbon, nitrogen, copper and aluminum and also from uncontrolled impurities (of the same elements, but also, e.g. of potassium and cobalt). After irradiation, these isotopes might preclude disposal in LLW repositories. Fusion power should be able to avoid creating high-level waste, while the volume of fusion ILW and LLW will be significant, both in terms of pure volume and volume per unit of electricity produced. Thus, efforts to recycle and clear are essential to support fusion deployment, reclaim resources (through less ore mining) and minimize the radwaste burden for future generations.

To me that says, "even though volumetrically there is more waste in fusion, it's lower radioactivity and more tractable"