What is the difference between a Relative order and a MidPrice order?

A Trailing Stop Limit order is designed to allow an investor to specify a limit on the maximum possible loss without setting a limit on the maximum possible gain. A "Sell" Trailing Stop Limit moves with the market price and continually recalculates the stop trigger price at a fixed amount below the market price based on the user-defined "trailing" amount. The limit order price is also continuously recalculated based on the limit offset. As the market price rises, both the stop price and the limit price will rise by the trail amount and limit offset respectively, but if the stock price falls, the stop price will remain unchanged. When the stop price is hit, a limit order will be submitted at the last calculated limit price. A "Buy" Trailing Stop Limit order is the mirror image of a sell Trailing Stop Limit, and is generally used in falling markets…

Relative (a.k.a. Pegged-to-Primary) orders provide a means for traders to seek a more aggressive price than the National Best Bid and Offer (NBBO). By acting as liquidity providers, and placing more aggressive bids and offers than the current best bids and offers, traders increase their odds of filling their order. Quotes are automatically adjusted as the markets move to remain aggressive. For a buy order, your bid is pegged to the NBB by a more aggressive offset, and if the NBB moves up, your bid will also move up. If the NBB moves down, there will be no adjustment because your bid will become even more aggressive and execute. For sales, your offer is pegged to the NBO by a more aggressive offset, and if the NBO moves down, your offer will also move down. If the NBO moves up, there will be no adjustment because your offer will become more aggressive and execute. In addition to the offset, you can define an absolute cap, which works like a limit price, and will prevent your order from being executed above or below a specified level…

The Snap to Primary (SNAP PRIM) order is similar to a pegged order, as the original order price is determined by the current bid/ask plus or minus an offset. But unlike the pegged order price, the "snap to" order price doesn't continue to peg as the price moves…

The Snap to Market (SNAP MKT) order is similar to a pegged order, as the original order price is determined by the current bid/ask plus or minus an offset. But unlike the pegged order price, the "snap to" order price doesn't continue to peg as the price moves…