Sea salt and table salt are different in a number of ways.

For example:

Sea salt is usually unprocessed and is created through the evaporation of seawater. Table salt is usually mined and undergoes processing for easier use in recipes.
Sea salt contains trace levels of minerals like calcium, potassium and magnesium. The minerals in table salt are removed during processing. However, it’s worth noting that the amount of minerals present in sea salt is minimal; if you’re looking to increase calcium intake, for example, sea salt isn’t going to make much of a difference. You’re better off getting these minerals from healthier foods.
Sea salt crystals are larger. If you were to compare a spoonful of sea salt to a spoonful of table salt, you’d notice that the larger crystals in sea salt leave more air space in the measurement – and thus, less total salt is used.

Having said all of that, there is one really big similarity: Despite marketing and popular public opinion (according to one survey, 61{967bf23b37ec6a673a83041540b3f904a815b4119ddf673afb961c1e7592ebdd} of respondents believed sea salt was a low-sodium alternative to table salt), both sea salt and table salt have the same amount of sodium content. And most of us are already getting way too much sodium.

According to the Centers for Disease Control and Prevention, the average daily sodium intake for Americans is 3,436 mg. Organizations like the American Heart Association recommend no more than 1,500 mg per day. We’re already getting twice that recommendation. So while switching to sea salt can provide some minimal benefits, we should really spend our time and effort reducing overall sodium intake – sea salt, table salt or otherwise.