When you render a scene, Blender does a series of calculations to determine what an image of your scene would look like from the viewpoint of the camera. These calculations take time, but it’s important to understand what rendering does.
The render button is not a “make my scene look more detailed” button.
Instead, it helps to think of it as a “take a detailed picture of my scene” button.
The reason a render looks good is that it stops and takes time to draw your scene. The reason you’re able to look around your scene freely before you render is that it’s not doing the same long calculations. Imagine how infuriating it would be to have to sit and wait for blender to do a full render twenty times in between camera pans!
There are a couple of ways to get a more detailed preview of your scene without rendering. These are closer to the final render, without taking nearly as much time.
My favorite way now is to turn on GLSL preview mode.
In the game menu at the top of the screen, enable “Blender GLSL Materials.” You can enable or disable options in the “GLSL Material Settings” submenu.
To activate the preview mode, hit Alt-ZKey. This changes your viewport shading to the “Textured” drawtype. It’s not a full render, and it won’t show procedural textures or raytracing, but it does show image textures, and updates lighting, specular highlights and buffer shadows in real-time.