Case of iPad

The air tech specs

Size and Weight2

• Wi-Fi
  • Height: 9.4 inches (240 mm)
  • Width: 6.6 inches (169.5 mm)
  • Depth: 0.29 inch (7.5 mm)
• Weight: 1 pounds (469 g)
  •  
• Wi-Fi + Cellular
  • Height: 9.4 inches (240 mm)
  • Width: 6.6 inches (169.5 mm)
  • Depth: 0.29 inch (7.5 mm)
  • Weight: 1.05 pounds (478 g)

https://support.apple.com/kb/SP692

The air 2 tech specs

Size and Weight2

• Wi-Fi
  • Height: 9.4 inches (240 mm)
  • Width: 6.6 inches (169.5 mm)
  • Depth: 0.24 inch (6.1 mm)
  • Weight: 0.96 pound (437 g)
• Wi-Fi + Cellular
  • Height: 9.4 inches (240 mm)
  • Width: 6.6 inches (169.5 mm)
  • Depth: 0.24 inch (6.1 mm)
  • Weight: 0.98 pound (444 g)

https://support.apple.com/kb/SP708

There are a few millimeters difference in the depth (thickness) so depending on your case it may. Portfolio cases would be OK, closely fit silicone or hard plastic may not.

The original iPad Air and iPad Air 2 models are both 9.4 inches tall and 6.6 inches wide when held in portrait (vertical) orientation, but the iPad Air 2 is slightly thinner (0.24 of an inch compared to 0.29 of an inch) and lighter (just slightly under a pound compared to just slightly over a pound).

So a case made for the original iPad Air, will like fit an iPad Air 2, but it may not fit exactly due to the Air 2 being 0.24 inch thinner.