What is an OPEN POSITION and how does it differ from a SPREAD?

Answer 1

An open position is any position that has been opened but has not been closed. It could be a long stock position, a short stock position, a long option position, a short option position, a long futures position, etc.

The word "spread" without qualifiers is usually used to indicated two or more open positions that offset each other. For example, a long stock position and a short call option combination, called a covered call, is a spread.

There are other uses of the word spread, for example a bid-ask spread, as noted in the first answer, is the difference between the bid price and the ask price for a particular security.

Answer 2

When you buy a stock option, you open the position, and you sell to close it. The spread is the difference between the bid and the ask price of the option.