Sometimes it doesn't matter which type of electric mixer you use -- when you are mixing something light like a batter, or whipping egg yolks, egg whites, or cream. You can do those easily with either a stand mixer or a handheld one. But when you want to mix something heavy and dense, like bread or cookie/biscuit dough, a stand mixer is the way to go. Stand mixers usually have stronger motors and beaters, and are more stable. So your first clue is: what is the recipe making?
You might be able to tell which they mean (if they actually prefer one type but don't tell you) by whether the recipe says to use attachments: if it says to use the paddle attachment or dough hook, most likely it means for a stand mixer. When it calls for a whip or whisk attachment, it's also probably a stand mixer -- I'm not sure if whips are standard attachments for handheld mixers.
But really, if one type of mixer will do the job better than the other type, the recipe should be specific about which to use. That's something I see (or don't see
) a lot in my work, and it drives me crazy. The cook reading the recipe needs to know what tools are best to use!!!!