I won't get into the 3rd versus 4th generation debate but Altium does have a unique approach. Altium's approach is holistic in terms of combining PCB, FPGA and embedded software development in a single design platform. This approach leads to a level of abstraction for creating an FPGA design with a schematic-like tool where you select IP blocks (ethernet, USB, 3G) from an IP pallette. You wire them together using an OpenBus that handles most of the design connectivity. When done the design moves to the Software Platform builder that creates the software stacks for the IP blocks in the schematic. You can also add your secret sauce in the form of HDL code, so the approach is not limiting. And, the IP library gets you 80% of the way there for many designs in a hurry. Check out Altium's Soft Design Methodology.
This sounds good. I would like to see more detail about how Altium Designer addresses several other issues in the Altera EDA tools forum thread
"Schematic entry (4th generation) vs. VHDL/Verilog (3rd generation)". We have seen too much embellishment in the past, so there are many skeptics. My name in the forum is SimKnutt.