"Zephyr" construction (also used on all Gitman button down and sport shirts), is a classic soft collar construction, consistent with American mansufacturing roots. It is softer. lighter and most comfortable.
The 80's 2-ply Oxford is actually a dobby weave which mimics an oxford construction. It allows the elegance of fine construction with a very light actual weigh. It is wearable in all climates at all times of the year.