A foodie who is a person who loves tasting, making, and talking about specialty foods as a hobby. These type of people enjoy finding obscure restaurants with unique dishes. They may also know about uncommon foods that enhance or provide an exotic twist to a common dish. Quality and uniqueness are the focus. 

Examples:

Oh! Did you try the new Thai-Japanese infusion restaurant? They have the most delicious maté ice cream. (spoken by a foodie)  

Ask Jack and Leah for a new restaurant suggestion, they're such foodies.

Gourmet is commonly used as an adjective to describe the quality and professionalism of the food.

He made her a gourmet meal for her on their 4th date.  

The new cafe has gourmet coffees. I'm drooling over just the thought of them. 

To me, when you say "gourmet", it sounds like a connoisseur of good food or drinks (tasty, up-scaled, good-quality sort of food). So if you say "gourmet", you eat a lot of good-quality food and you know that it is.

"foodie" is similar but it refers to someone who just likes eating food. In general, it implies that someone enjoys eating food a lot with/without caring about the quality. 

-------------------------- update: someone pointed out I used "gourmand" so I updated it to "gourmet". I meant to say "gourmet" :)

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Thanks

~ Murad