It is important to understand the difference between watches and warnings. According to the National Weather Service here are the differences between severe weather watches and warnings.

Severe Thunderstorm Watch

A Severe Thunderstorm Watch is issued when severe thunderstorms are possible in and near the watch area. It does not mean that they will occur. It only means they are possible.

Severe thunderstorms are defined as follows:
1) Winds of 58 mph or higher
AND/OR
2) Hail 1 inch in diameter or larger.

Severe Thunderstorm Warning

A Severe Thunderstorm Warning is issued when severe thunderstorms are occurring or imminent in the warning area.

Severe thunderstorms are defined as follows:
1) Winds of 58 mph or higher
AND/OR
2) Hail 1 inch in diameter or larger.

Tornado Watch

A Tornado Watch is issued when severe thunderstorms and tornadoes are possible in and near the watch area. It does not mean that they will occur. It only means they are possible.

Tornado Warning

A Tornado Warning is issued when a tornado is imminent. When a tornado warning is issued, seek safe shelter immediately!