Are EDT and EDP just the difference in concentration?

Are EDT and EDP just the difference in concentration? 

Each major brand will produce EDP or EDT these two concentrations, some brands have the same taste and even EDP, EDT. Some brands EDP and EDT do not make big adjustments to the raw materials, so they smell about the same. But many salon incense brands will adjust or upgrade the raw materials, so that the taste of EDP smell more depth and level. 

Therefore, in the choice of EDP and EDT, maybe just try the fragrance is the most accurated way.