'Wine glass', 'horse race' and 'race horse' are all examples of compound nouns. When you have a compound noun made up of two words, the second word tells you what the object actually is - for example, a 'wine glass' is a kind of glass. The first word (wine) tells you what kind of glass it is. It's a glass which you drink wine out of. Likewise, a 'race horse' is a type of horse. The first word (race) gives you more information about what type of horse it is. By contrast, a 'horse race' is a sort of race. The first word (horse) specifies the sort of race that it is. Here's a little exercise for you: Using the rule above, what would you call a glass you drink whisky out of, a horse that works on a farm, and a race involving bikes? So, what's a 'glass of wine'? It's a glass containing wine. And what's the difference between a 'wine glass' and a 'glass of wine'? Simply, the first is empty and the second is full.

A wine glass = Refers to the actual glass itself that is used for drinking wine. Example: Jeff took a wine glass from off the shelf. A glass of wine = A glass(most likely a wine glass like earlier) that is filled with wine. Example: Luis ordered a glass of wine from the bartender. A horse race = 1.Is the event itself, where horses race against eachother. 2.Can also be used as an expression to describe a highly competitive/intensive activity. Example: 1. Luis and Jeff attended a horse race and bet all their money "Lucky 7". 2. It was a horse race trying to get home before everyone else. A race horse = A horse used primarily for racing in events such as horse racing. Ex: Carla began training Bingo into a race horse so she could extra money on the side.

Running "wine glass" or "glass of wine" through Google Translate, I get: "Un vaso de vino" o "Un vaso de vino" <== this explains your confusion The definition of a "wine glass" is "un vaso para beber vino". I would be tempted to say "un vaso por vino" for "wine glass" but my Spanish is not very good so I'm uncertain if that is correct. A horse race is "Una carrera de caballos" A racehorse is "Un caballo de carreras" In English, a "wine glass" is a glass for drinking wine. It has a specific shape. Look up "wine glass" on Google Images. The wine glass may be empty or full. A "glass of wine", on the other hand, is a glass that has at least some wine in it. The assumption is that the glass is full of wine. Also, "a glass of wine" is usually a "wine glass" with wine in it. If the glass is not a "wine glass", one would say something like "a drinking glass of wine" or "a cup of wine", etc.