I would like to know if they are the same thing and if they are not what makes them different?
No, there is a subtle difference between the two.
A Wah Pedal (e.g. Dunlop Cry Baby) works by emphasising a specific frequency range and diminishing others. The frequency range that it does this to is dependent on the position of the footpad. If it is pushed forwards it will highlight the treble frequencies and if it is moved backwards then it will highlight the lower frequencies. By changing the rhythm pattern that your foot moves in you can highlight different notes and create effects (Like the 'wah cah chi cka' noise).
An envelope filter is more commonly known as an Auto-Wah or Q-wah among guitarists (e.g. Boss AW-3). These work similar to a wah pedal but shape the sound depending on the volume or just at a regualar tempo rather than the position of the footpad - instead of a footpad they have controls for sensitivity, tempo and/or decay depending on the model.
In summary, you would want to use an auto-wah either because you don't have to control it while playing or because it can have more precise and intricate changes of shape than you can do with your foot. A wah pedal though can allow you to be more expressive (e.g. when playing a repeated phrase you can slowly move the pedal forwards to create a morphing sound - something an auto-wah couldn't do).
Here are video demos of the two pedals I mentioned above so you can see what they look like and how they work.