Just to reiterate Ryzen 3/5/7 is not enough to tell you the core count. You need to know the series also.
Currently the CPU suffixes are U, G , X and no suffix. U (low power mobile APU) and G (desktop APU) so far are all Raven Ridge a single 2-4core CCX + GPU. There is talk of an H series high power APU but it hasn’t showed up yet.
X and no suffix are the desktop parts Summit and Pinnacle Ridge the X denotes extra boost via XFR. Which are 2 CPU CCXs (Core complexes) on a single die.
There is also Threadripper as well which is 2 desktop dies up to 4 dies on Threadripper 2 wired together on a single package with 4 memory channels and 64 pcie lanes. EPYC is 4 dies with up to 32 cores the main difference from threadripper is 8 channel memory and 128 pcie lanes. EPYC has a very similar pinout but doesn’t seem to work in threadripper motherboards, the motherboards for it are also generally very high end server boards as they have to support all that massive amount of IO.
Edit:
Ryzen E series have recently been announced that have lower clocks and much lower power use these are desktop parts. Also I forgot to mention there is also Ryzen GE sereis which is roughly the same as the G series. As well as V series which has partnumbers like V1000 etc… these are embedded versions for the raven ridge core.