Olympus OM-D series

• The PEN series is smaller and lighter by average.
• Most PEN cameras have fewer features than the OM-D cameras.
• Every OM-D camera has a built-in electronic viewfinder, in the PEN there is only one model with it (PEN F).
• Every OM-D camera has a flash hot shoe, whereas not all PEN cameras have one.
• Most PEN cameras have a 3 axis sensor stabilization system, whereas every OM-D has a 5 axis one, with one exception (E-M10).
• The PEN series has a "rangefinder-style" body (flat top), whereas the OM-D series has an "SLR-style" body (bump on the top).
• Usually the OM-D line is higher-end and more expensive than the PEN line.

There are three main categories in the OM-D series:

• E-M10

   

  • The lowest-end OM-D category.
  • Beginner-friendly design.
  • Built-in flash.
  • Least expensive.
  • In absolute terms, a mid-range line.
  • Newest model: E-M10 Mark IV.
• E-M5

   

  • Mid-tier in the OM-D family.
  • Made for enthusiasts.
  • Weather resistance
  • Moderately expensive.
  • In absolute terms, a high mid-range line.

• • Newest model: E-M5 Mark III.
• E-M1

   

  • The highest-end OM-D category.
  • Professional design and professional features.
  • Large grip.
  • Most expensive.
  • Advanced video features.
  • In absolute terms, a professional line.
  • Newest model: E-M1 Mark III.
    • E-M1X

       

      • Highest-end OM-D camera based on the E-M1 Mark II, introduced in 2018.
      • Built-in vertical grip.
      • Very ergonomic handling and button layout.
      • Very large EVF magnification.
      • Almost twice as heavy as the E-M1 II.
      • Long battery life.

The main difference between them is the ergonomics and the customizability. Most of the features are present all across the OM-D family, but the handling, the durability, and the accessibility of the features differ in favour of the more expensive categories.