The Meostars are alluminium bodied and the range includes the larger lens and variable power scopes many if not of which (I haven't checked) are FFP reticle. The artemis are steel bodied.
I have a Meostar R1 and an Atemis 6X42 and there is no discernable difference in optical quality or build quality. Both are excellent and both have 30mm tubes, the Artemis is just heavier.
The Meopros are alluminium but have 25mm tubes. The Meopro 4-12 X 50 is an overlooked general purpose stalking scope and very good value for money. Its also a cracking HMR scope. Again excellent glass quality for the money.