A Stop-Loss is a defensive position - it serves to protect against loss.  However it does not "lock in" gains. 

You can purchase a stock for $20 with a Stop-Loss of $15, however if the stock rises to $30 then drops back to $20, unless you sold at $30, there was no real gain, since gains or losses are only realized when the stock is actually sold.

A collar protects profits while also minimizing losses.  When a stock is "collared", it is automatically sold when the price rises by 10% or drops by 5%.  Until one of those limits is reached, it remains in a team's portfolio.

This "locks in" your profit by automatically selling when the gain is 10%, or stops your loss by automatically selling when the loss is 5%.