As for Blender Eevee, Cycles, and Poser.

Blenders main render engine is still Cycles and Poser has SuperFly a migrated sister of Cycles.

If migrated to Poser, EEVEE would replace the preview render engine.

The Blender team is still improving on Eevee before the final release, and more and more Cycle nodes are becoming available in the Eevee preview.

Eevee = Preview

Cycles = the full bore all out render engine.

Best regards, Tony