Are wireless speeds on Laptop and iPhone the same? This might be a network forum question, nor sure but here is my question:
My router is AirPort Time Capsule, the new model that has wireless ac.
My laptop is Retina Macbook pro and looks like it also supports wireless ac
and my phone is iPhone 6 and I think that one is also wireless ac.

Why when I go to SpeedTest application on the iPhone my speed does not show higher than 20 or 30 Mbps but when I do speediest on browser on MacBook then it goes to 50, 60, or 70 Mbps?
It would largely come down to the hardware components (i.e., related to wireless communication) that each device is composed of.

From the Apple store, you can inspect the list of components within a given device. You want to identify the specific part number/name and the manufacturer. Some device review sites might provide that info as well.

You can then go to manufacturer sites and reference the specific parts, and learn more about the specifications for each part. Doing this comparison, this should answer your questions about the varying performance that you're observing.

Also keep in mind that newer versions of the same hardware model can have more advanced wireless components, which improves performance in the newer product (even though it appears identical to the older model).