I think that's just semantic misunderstanding. Some people name as "idea" the combination of concept + execution proposal. Other's name "idea" as the concept alone. I don't think there's a right or wrong here, people just have different opinions of how to call what.

Personally, for practical purposes and pushing myself forward, I prefer calling idea something that has a clear execution strategy. If you have a brilliant concept but not sure how to put it in practice. Then in my opinion you got half an idea, and should work on the other half.

Ideas and execution are not independent. For example, it is easier to execute an idea that you believe in rather than one you don't. (In a vacuum it may seem strange to think that someone would execute an idea that they don't believe in, but realize that this happens all the time, perhaps the majority of time). Another example, it is easier to execute an idea which actually has a market - the enthusiasm of customers is infectious and highly motivating. Final example, execution is better when the idea 'goes with the grain' of available technology (if it's a technology idea, of course).