The difference is in the approach but at the end the "same" OpenStack will be installed
I explain. Mirantis has packaged the installation of OpenStack in a custom ISO based image so you dont need to lose time in a huge configuration.
Mirantis developed Fuel which is a set of many components : Astute, nailgun, and so forth (please chech official documentation)
Mirantis allows to install OpenStack in a very easy and automative fashion.
Of course the packages of nova, neutron, cinder are the same even if they are embedded in mirantis custom repo.
I suggest you to try to install OpenStack manually dor learning purpose