No strength and power are not interchangeable. Strength is the how strong you are. It is usually best measured by the maximum weight you can lift. As such, strength is very much a quick twitch muscle sort of thing.
Now power is sort of strength over time. Think of the amount of weight you can lift per hour.
So you can have a very strong person who can lift say 400 lbs but whose power is less then another person. Actually that is very common.
Strength is about quick twitch muscles and muscle size.
Power is about aerobic conditioning and slow twitch muscle fibers.
In cycling, it might be comparing a sprinter to say someone doing an hour time trial. Very different sorts of things.