oh yeah, they are different!
Potting soil is man created and varies by company. It is usually a mix of peat moss, inorganic material such as perlite or vermiculte and compos and perhaps sand.....depending on brand. Slow release fertilizer may also be added. Potting soils may have been heat treated.......pasteurized.......to reduce disease potential.
Top soil ideally is the organic, biologically active top layer of the soil where plant material is being composted and mixed with .........worm poop......and other items. The top soil layer will very in depth from nearly nonexistent in desert areas to several feed or yards deep in rich alluvial soils. Top soil is vital to the biological and to some extent, chemical, processes of the soil. (see Soils 101 in college)
Not all top soil is black tho often is. Other soils, devoid of organic component are passed off as topsoil....for example river silt.
Garden soil is what is found outside. It will vary in texture, biological nature, maybe contain top soil (but that might have been stripped and sold off when the house was built). Garden soil may contain a variety of weed seed, insect eggs/larvae/ and disease spores as it has not been pasteurized (it can be done though). Ideally the good garden soil will also be biologically active with helpful organisms to help control the bad and to provide that biological and chemical aspect of soil.