I bought my first shoes for spin, so they were mtb shoes with spds. I used them on my first road bike, with spd pedals. When I upgraded to a nicer bike, I got Speedplay pedals and road shoes and kept the old ones for spin. They were really too small for me, which I didn't find out until I bought a mountain bike and tried to wear them with thicker socks in the fall. So I got new mountain shoes, which, of course, I still use for spin.
I think you will find it easier to start with the one (spd's) and wear mountain shoes for road riding and then add in the road shoes/pedals when you feel comfortable. Of course, not everyone needs to do this, but I found once I had the confidence riding on the road with spds, it wasn't any transition to the Speedplays.