User blog comment:Somethingmorethan/Useless SpongeBob facts/@comment-24438956-20141005003525/@comment-25492127-20141005155600

Simply put, subtitles are unformatted (usually centered and on the bottom of the screen in white plain text) and are used mostly for dialogue (except for Deaf & Hard of Hearing subtitles, which includes things like sound effects) and primarily use hyphens to show a change of speaker.

Closed captioning is formatted (can be pop-on, paint-on or roll-up; can be placed anywhere on the screen [in a grid of 32 characters wide and 15 characters high] and be justified left, right or centered, can be any basic solid color, can be bold, italicized or underlined, etc.) and is enabled on a TV through the TV's settings (or by the set-top box, if supported), with 3 main options: CC1, CC2 and Mute; CC1 is the most common captioning option and is usually the only one broadcasted, has normal English captioning; CC2 contains a secondary language, like Spanish, if the broadcaster has CC2 captioning for that program; Mute only enables captioning when the TV is muted. Closed captioning is geared towards deaf and hard of hearing viewers, and thus contains many descriptive details like sound effects, tone of voice and other things they might miss with their lack of ability to hear, and is far more certain on change of speaker (and can also be a number of different ways to show it, ">> [dialogue]", "- [dialogue]", etc.). However, since this is integrated in the broadcast signal, the limit is 32 characters per line, and only 4 lines can be on-screen at a time (regardless of where they're placed).

This is just a bare description of each, but you get the point.