In Chinese, pubs and nightclubs are both referred to as bars and I've always assumed that would be wrong or weird in English (even in the past), but then again both establishments have a bar (as in barrier or counter) of equal importance.
In the United States, "nightclubs" tend to serve alcohol and meals, and also have a dance floor. They have tables, and also a bar you can sit at." They also tend to be pricey.
"Bars" often serve both alcohol and meals, although some serve only alcohol and snacks (bagged chips, etc.). Many have tables, although some only have a bar and a very limited number of tables. They do not have a dance floor, although sometimes an area is set aside for dancing, although it is not in any way different from the rest of the bar, other than not having tables. Bars are generally more downmarket.
In the United States, most people would make a distinction between "bar" and "nightclub". (Keep in mind that hotels can have a bar or a nightclub, or even both.)