Data fusion/Pansharpening of Sentinel-2 and PlanetScope

I am working with fusing optical (Sentinel-2 and PlanetScope) and radar data (Sentinel-1) for my study area, but I got a bit confused over the definition of fusing in the literature.

There are plenty of pansharpening techniques to improve the resolution of satellite imagery and I am using one of these methods on Sentinel-2 with PlanetScope image as PAN image. Is the resulting product now a fused Sentinel-2 and PlanetScope image?

Is pansharpening synonimous with fusion of satellite images or are there more applications needed to fuse two satellite images with different resolutions?