The most important difference is that LDD is Lego's own official product available for free from ldd.lego.com. Unlike the other apps mentioned LDD is not open source. This is a drawback because there is no way to hack it and insert new bricks for example. This is also a plus because hacking is not required - you just need to download and install it. Another plus is that it is well integrated with other services from Lego. What you build can be uploaded into a public gallery and even bought as real bricks (depending on your country).
- You get a photorealistic view while building.
- LDD models the physics of elements. You can put bricks only where they fit. They can be rotated or selected based on connections. It does not model rotating gears, though.
- The ready model can be rotated or viewed between different backgrounds. Since this is built into the app it is convenient, but our images will not be as nice as with the LDraw - Pov-Ray duo.
- After a click and some thinking it presents you with building instructions too. Handy if you are about to order physical bricks.
After starting it you have to choose whether to build from Factory, Mindstorms or Creator bricks. Building from the Factory bricks allows you to order your creation online from real bricks. If you made up your mind, you can choose from half-ready models, starting from scratch or from your own earlier models.
On the left hand side you can choose the bricks - not all of them are available in all colors, this limits building a little bit. Technic elements are very rare, the selection support City-style building most (in case of the Factory bricks).
You can place new bricks with the mouse and rotate them with the arrows. The program helps you to attach new bricks to existing ones. In the Tool Box there are the following tools available:
- Select. Selected bricks can be rotated and moved the same way as new ones. You can select single bricks, bricks within a rectangle, connected bricks etc.
- Clone. You can copy without limits.
- Hinge. You can rotate parts like propeller, arms and legs of minifigs, etc.
- Paint. If the selected part is available in other colors, you can re-color it.
- Screen shot.
Once this is done you can go to view mode, rotate it and make pictures:
In Building Guide Mode it even creates building instructions that can be saved as HTML:
When done you can upload your model to factory.lego.com (after registration). You can even order your own or others' sets - it is not more expensive than a factory set with the same number of bricks.
- LDD does not let you build if the bricks do not fit. There are some borderline cases though that fit in reality but not according to LDD.
- With larger models it happens sometimes that small errors accumulate and some bricks do not fit unexpectedly. For example I have managed to save a design that LDD could not load the next time because of this.
- Bricks available in the Factory change a little bit over time. It is possible that you could order a set yesterday but not today.
- Create building instructions may take minutes if the model is large.
- A "Mirror building mode" would be very useful - SR 3D Builder is better here.