Additional features and improvements in Construct 3 that you won't find in Construct 2.
You can import your Construct 2 .capx files directly in to Construct 3 and carry on working with all the new features and improvements. Just drag-and-drop your .capx file in to Construct 3 to open it. See Importing Construct 2 projects in the manual for more details.
The new runtime is also backwards compatible with Construct 2 games, so all your existing games can benefit! See the manual entry on The C3 runtime for more details.
Build your Android APKs directly from the editor, ready for publishing. You can also download Xcode projects for iOS ready for testing and publishing to the Apple App Store. There are also new exporters for publishing Facebook Instant Games or Playable Ads.
The new runtime also provides a range of brand-new plugins and behaviors:
Use BBcode markup to style text in your game. Styles include bold, italic, underline, strikethrough, changing font face and size, custom background, text and outline colors, and position offsets. Combine all of these for exciting animated text effects! See the blog post New text features in the C3 runtime for more.
Oh yes, and you can also import Web Fonts in to your project and use them directly in the editor - even using multiple custom web fonts in the same text with BBcode!
Add exciting new visual effects to your games by deforming the appearance of objects. You can split up objects in to a grid of points and move the points around to distort them. Use it in the editor to enhance your level designs, or alter meshes dynamically at runtime for impressive new animated effects. Learn more in the blog post Have you heard about meshes?
Add elements of 3D to your projects. Use Z elevation to move any 2D objects or layers up and down on the Z axis. Add the new 3D shape plugin to your project for a further 3D appearance. Go even further with 3D mesh distortion. Learn more in the tutorial Using 3D in Construct.
Use the new scene graph feature to build complex hierarchies of objects that move, scale and rotate as one. Conveniently design hierarchies in the editor. Create entire hierarchies at runtime with the new Create hierarchy option. Assign and change hierarchies at runtime as a new alternative to the Pin behavior. Learn more in the blog post Let's talk about the scene graph!
You've found the right tool — Now start making games!