Active production — no obsolescence risk for new designs
That means TI is still manufacturing it, and there is no announced last-time-buy or end-of-life notice. For a BOM line, this part can be specified into new designs without worrying about a near-term discontinuation. If you are already using it in production, the supply channel is stable through standard distribution.
Open-drain output — wired-OR and level translation
The open-drain output lets you connect the reset pin to a pull-up resistor tied to any voltage up to the absolute maximum of the output transistor. This is useful when the supervisor runs from one supply but the reset input of the monitored IC runs at a different logic level — the pull-up rail sets the high-level voltage. It also allows multiple open-drain reset outputs to be wired-OR together, so that any fault condition pulls the shared line low.