What is the difference between Marine Corps Boot Camp and Ranger School?

Parroting a previously posted comment: Apples to Oranges.

But, here's the fundamental difference(s):

1.) Marine boot camp is designed to build a civilian into a basic Marine. The training is focused to get every body (not "everybody") to graduation day. The next phase is usually School of Infantry (SOI), or their MOS school. All infantry-contracted Marines go directly to SOI. Non-Infantry Marines will, likely, attend SOI or MCT school within a year of reporting to "the Fleet" --after their MOS school. The boot camp syllabus is geared to the lowest common denominator and maximum graduation rates are the goal.

2.) In Ranger school (like OCS), the student must come already physically & mentally fit. The course is designed to elevate the performance of already established top-performers. Attrition is expected... and to a point, encouraged. No attrition = No morale. In boot camp, the recruits are trained how to eat MRE's. At Ranger school, they teach you how to identify safe-to-eat plants ...and animals.

And the last video

I never went to Ranger school, but when I was in Marine Boot, our Drill Instructor raved about Ranger school and what a great accomplishment it was for him to go. I doubt a high speed Drill Instructor would speak highly of a school reminiscent of being back in boot camp. That said, I have to wonder if this is just trolling for angry responses, or just an attempt to make fun of Marines that reminisce about boot camp much the same way the girl in American Pie remembers band camp. Also, it is highly unlikely that a person off the street is going to make it through Ranger school, but by definition, that is everyone that goes through boot camp.

Well you need to learn to read. Marine boot camp isn’t anything like Ranger school. I had a Marine as my Ranger buddy in school. I was an e4 and he was e6. He quit. Couldn’t make it through Florida phase. I was in a recon platoon in the 82nd and he was Force recon. If it was like boot camp I would think he wouldn’t have any trouble but out of the entire graduation class I think only one or two graduated. I don’t think any of them were first time goes. I think there was about 30 of us that were.

I work as a Series Commander at MCRD San Diego. Marine boot camp is entry-level training geared towards making basically trained Marines and its more mentally taxing than anything. The physical fitness events aren't terribly difficult on their own, in my opinion. However, augmented with "Incentive Training", which can be given every hour during the day with some exceptions, it gets physically demanding. We push them harder than most have been pushed before and build from a 3mi, 5mi, and 8mi hike under load to a 14 mile hike during the Crucible. The Crucible would be the notable exception for difficulty the 54 hour event has recruits are marching over 40 miles, completing dozens of events, and getting 4 hours sleep at night. However, the training is focused on giving Marines basic skills, not in-depth tactical training. They learn how to shoot, but they're not learning anything too varsity. What they're REALLY taking away with them is the discipline, espirit de corps, and the instant willingness and obedience to orders that are the hallmarks of the Marines. Keep in mind, we have everyone from truck drivers to cooks to grunts and artillerymen starting here and we have our own unique flavor since every Marine is a rifleman, but their real tactical will be at the School of Infantry following boot camp.

Ranger School, from what little I know from my own friends in the Army and watching programs on the course, is much more physically difficult. It isn't the shock and awe of the Marine DI screaming in your face 2 weeks removed from your comfortable civilian life, but rather the slow taxing toll of the combat patrol in multiple environments with little food, little sleep, and in-depth instruction to make ADVANCED infantry. Since you're dealing with a pool of candidates who are already military professionals, it's a far different beast and the fact that it makes professional infantrymen tap is impressive. The closer comparison would probably be Marine Basic Reconnaissance Course or BRC though certainly Marine Infantry Officer Course is an impressively difficult course as well.

Each has their merits and are difficult in their own right, but like many other people have said, they have vastly different missions.

Gonna take a stab at this...
Range School is Instructed by Army Rangers.
Marine Corps Boot Camp is Taught by a bunch of Sadistic Humans that lose their voices about two days into the job.