The cheap battery is a single small low current cell. Its rated nominal charge/discharge rate is 0.2C (it's 400mAh so that's 80mA). You'd be looking at about 5 (400mAh/80mA) hours to fully charge at the nominal current. It is designed to be used in applications where it discharges at that sort of rate as well.
The expensive battery has a far higher capacity and multiple cells. They also have significantly higher rated currents. They are rated at 20-30C rates, that means applications where the battery is drained in a couple of minutes not the 5 hours of the cheap cell.
So very different batteries for very different applications. One is for keeping a low power device running for multiple hours. The other could do that but is designed for something that takes a lot of power very quickly.
On to the chargers:
The small simple cell/charger will charge a single cell at a fixed (fairly low) rate regardless of what that rate that cell can take.
The more complex system can cope with multiple cells (up to 6) at multiple different rates. That is adding a lot of extra complexity which means extra components and cost. It also includes a housing and user controls, the mechanical parts and then assembly and testing probably cost as much if not more than the actual charger electronics inside it. And since it's being sold as a product rather than a bare component has to be tested to verify it meets various regulatory requirements. That adds further development cost that needs to be made up somewhere.
For 2.5 times the price you get something with well over twice the functionality.