Grenada itself is totally different from the BVI. Very big liveaboard community that rarely sails anywhere around Grenada. A few bays and beach bars on the south coast but very little anywhere else. Grenada is brilliant as a base for a boat as you can get anything done there at reasonable prices.

Once you leave Grenada itself and head north into the Grenadines, you will have to do a bit open water sailing but the only real stretch of open water is going between the north of Grenada and Carriacou or Union. After that you have mostly got an island to windward that keeps the waves down with the wonderful Tobago Cays, Mayreau, Bequia and Mustique plus many more, all of which have good, sheltered anchorages with bars and restaurants.

It is not the same as the BVIs. To be honest, nowhere in the World is like the BVIs for its easy sailing, short distance between beach bars and easy sailing with almost guaranteed wind.

In conclusion, if what you want is the BVI experience of get up, sail for a couple of hours, stop for lunch and a swim, then sail/motor for another short while then pick up a mooring ball and hit the beach bars, then stay in the BVI because you won't find anything quite like that elsewhere. If want a bit more variety and are willing to sail a bit more to get that then the combination of Grenada and the Grenadines are close to perfect.