At what proficiency level? Marine Corps pipeline is longer by some significant measure. Just looking at IET+AIT type scenarios for Infantry Only.
USA Army Boot Camp 10 Weeks
Marine Corps Boot Camp 13 Weeks
______________________________________
Infantry AIT 12 Weeks
(As of 2019)
Marine Corps SOI-ITR
8 Weeks
So Infantry Soldiers receive 22 Weeks of training before first unit assignment and Infantry Marines receive 21 weeks. Prior to 2018 pilot program that was adopted in 2019 for Infantry and Armor Branched Soldiers, Infantry Soldiers only received 14 weeks of training before going to a follow on school (airborne) or their first unit. Now the training an Infantry Soldier receives is comparable to an Infantry Marine. So in all actuality, previously you could probably say Marines were more expensive to train.
(Jesus, I wish Scouts had 22 weeks of training when I was in the Army, there'd have been a lot less fat ones showing up as privates when I was a PL)
Also in my experience, Marine Officers are more expensive to train compared to Army Counterparts. For everyone but Academy Grads (OCS+TBS+MOSQ) vs most Army folks ROTC (LDAC*+MOSQ).
*West Point Graduates fulfill the equivalent of the LDAC requirement but it's in the West Point Curriculum.