Welcome to FT!, coloradotraveler

The two approachs are very different.

Use the Chase portal, you are purchasing a "cash" ticket and the points are used to offset the cash transaction.

Move to UA and you will purchase an award ticket with the points converted to UA MP miles.

You will need to research the "price" of each method. One may be better than the other this week but next week it may be different.

The cash tickets will be mileage and status earning, the award ticket will not.
The award ticker will have lower cancel and change fees than the cash ticket.

The points once moved to UA can only be used for UA tickets,
The points at Chase have more flexibility in there use.

Simple, huh?