LinkIt is development platform that supports a range of chipsets, including the MediaTek MT7687F, MT7697 and MT7697D for IoT devices and MT2523D and MT2523G for Wearable.
Linkit2523 is actually called LinkIt 2523 HDK, is a fully functional development board for wearable application prototypes powered by MediaTek MT2523G, an ARM Cortex-M4 processor with FPU that provides Bluetooth EDR/LE and GNSS. The board offers a touch display and extension connectors to battery and sensors.
MT2523 is actually the MediaTek chipset that is used in the end-product for wearable applications.
Linkit 2523 (HDK) supports and can be used for the smartwatch development. But by itself, it's a Hardware Development kit so you will eventually have to move from HDK to making your own PCBA with MT2523.