Pixel size is (as it sounds) the size of a pixel in the units of the raster's projection. So there is nothing you can infer from just the number, 0.00027 < 0.6 might mean that the first raster is higher resolution or it may mean one is measured in feet and the other in metres (or degrees or furlongs).
Here is the gdalinfo output for a raster I have:
Have a look at OpenDroneMap.
Drone Mapping Software
Generate maps, point clouds, 3D models and DEMs from drone, balloon or kite images.
Open Source Toolkit for Processing Aerial Imagery
ODM turns simple
point-and-shoot camera images into two and three dimensional
geographic data that can be used in combination with other geographic