The first is the 802.11 spec your MacBook Air supports (802.11ac) as well as how many streams it supports. In this case it is a single antenna (one stream per frequency 2.4 & 5.0 GHz). The MacBook Pro 15" has two WiFi antenna's
[image|1295831]
MacBook Air 13" Mid 2014 (WiFi - 1 & Bluetooth)
[image|1295832]
MacBook Pro 15" Mid 2014 (WiFi - 2 & Bluetooth)
So the data rate will be limited here depending on your Routers access point (AP) supports. Some Routers don't support MIMO.
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I would recommend you get a good WiFi analyzer to see what your AP is offering and run the app on each Mac to see what each is able to run at. This is what I use: [https://itunes.apple.com/us/app/wifi-explorer/id494803304?mt=12|WiFi Explorer]
You have a few different issues here.
The first is the 802.11 spec your MacBook Air supports (802.11ac) as well as how many streams it supports. In this case it is a single antenna (one stream per frequency 2.4 & 5.0 GHz). The MacBook Pro 15" has two WiFi antenna's
[image|1295831]
MacBook Air 13" Mid 2014 (WiFi - 1 & Bluetooth)
[image|1295832]
MacBook Pro 15" Mid 2014 (WiFi - 2 & Bluetooth)
So the data rate will be limited here depending on your Routers access point (AP) supports. Some Routers don't support MIMO.