Grain growth in metal is vital to its properties so the grain growth in the direction of build distinguishes, so far as I know, the Arcam builds from others. Directional grain growth means the final product is anisotropic. Wood is an example of an anisotropic material, it's properties are dependent on orientation.
Build chambers in the Arcam units are heated to, if my memory is correct (I didn't take notes), about 1000 C. so there's slower cooldown after the part is built. I don't know right now if that confers an advantage. Grain size and orientation in the presentation _appeared_ to give advantages in both hardness and strength as grain boundaries were offset like in a brick house. Clean-up after a part build involved blasting with the Ti powder itself for some parts.
They also obtained very near full-density results with a process they didn't describe in detail. Density was dependent on the quality of the powder and Arcam's recent acquisition makes the best. So, best density was obtained with Arcam's powder and further enhanced with the Honeywell process to obtain virtual full density. They said they reuse the blast powder and powder blasted from manufactured parts. No statements were made about build quality from reused blast Ti powder.
Sciaky's closed loop process allows continuous alteration of proportion of metals in an alloy to make parts with advantageous local properties, say toughness and hardness where they are needed. To control the proportions during the build adds another dimension to metal AM. Whether that's possible with Arcam processes now, I don't know.
I understand that laser units do not have as much total energy sent to melting the medium but energy density is higher because the laser beam diameter is so small. Build speed is slower, as far as I know, than in EB. Laser AM has the advantage that very fast cooldown occurs so very small metal grains are possible. Whether directional grain growth occurs or is possible, I don't know. In general, the smaller the grain the harder and more brittle the metal.
In my opinion, the momentum is in favor of Arcam EB for these parts manufactured by Avio and Honeywell. Both have found that they can make these parts faster, cheaper, lighter, and stronger than with traditional methods. The FAA has approved these parts made in this way. (Link or citation needed! I read this somewhere but don't know where). The Avio turbine blades are small enough that I don't see a real advantage in the Sciaky process.
