'Global price' is a generative term used for any SCIC-IRT ticket, while SCIC-IRT=Special Conditions of International Carriage for Integrated-Reservation Tickets. What does that mean? Key term here is 'integrated', meaning that there is a uniform fare combining actual ticket fare, seat/bed reservation and any potential surcharge (-->all in one, printed on a single ticket sheet) and it is calculated not on the bases of usual tariff tables, but per each connection per each segment, so it doesn't strictly depend on #km per route. While SCIC-NRT (previously known as TCV) on the contrary is based on tariff tables (#km/fare) + seat/bed reservation, as well as any surcharge, is a separate things here, which can be bought additionally in case necessary
Global price is usually not a good thing, exactly because such tickets are issued for a specific train with compulsory reservation, so you can use SCIC-IRT ticket only on that specific train and date --> restraining flexibility, while SCIC-NRT (=non-integrated) are flexible and not tied to any specific train, so you can just buy one through ticket and make stopovers along the way, choose any train you want etc. Another disadvantage of Global price (SCIC-IRT) is sort of hidden price increase, since per each segment of your route you need a new ticket, while with SCIC-NRT you can fully enjoy regressive nature of tariff and have a through ticket. Meaning that for instance 3 separate short distance route global price tickets (A to B, B to C and C to D) are obviously will be more expensive than one through SCIC-NRT (A-D via B and C). Clearly SCIC-IRT is more preferable for rail companies, since it allows more control. SNCF, FS or RENFE just make a compulsory reservation for all the long-distance high-speed trains and more or less restrict passengers capabilities to maneuvre. Then on trains for which SCIC-IRT is used rail companies in addition restrict use of any other tickets (besides a few exceptions, like Interrail or Eurail passes), thus forcing passengers use global price.
Maybe as a sort of general example you can take a look at conditions applied for
BWE and '
Jan Kiepura', for both SCIC-IRT is used, it might give you a better understanding on how it works in practice