What is the difference between UMTS and 4G?

UMTS is basically a version of 3G while LTE is based on the 4G network.

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GSM (Global System for Mobile Communications) is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (2G) digital cellular networks. The GSM standard is more improved after the development of third generation (3G) UMTS standard developed by the 3GPP. 

CDMA (Code division multiple access) is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdma One, CDMA2000 (the 3G evolution of cdmaOne) and WCDMA (the 3G standard used by GSM carriers), which are often referred to as simply CDMA, and use CDMA as an underlying channel access method.

TDMA (Time division multiple access) is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same transmission medium (e.g. radio frequency channel) while using only a part of its channel capacity. TDMA is used in the digital 2G cellular systems 2G cellular systems such as Global System for Mobile Communications (GSM), Personal Digital Cellular (PDC) and iDEN standard for cellular phones.

EVDO (Evolution-Data Optimized or Evolution-Data Only) is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. It uses multiplexing techniques including code division multiple access (CDMA) as well as time division multiplexing (TDM) to maximize both individual users' throughput and the overall system throughput. It has been adopted by many mobile phone  service providers around the world – particularly those previously employing CDMA networks. EVDO was designed as an evolution of the CDA2000 standard that would support high data rates and could be deployed alongside a wireless carrier's voice services.

UMTS (Universal Mobile Telecommunications System) is a third generation mobile cellular technology for networks based on the GSM  standard. Developed by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the International Telecommunication Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS employs Wideband Code Division Multiple Access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators. UMTS specifies a complete network system, covering the radio access network (UMTS Terrestial Radio Access Network, or UTRAN), the core network (Mobile Application Part, or MAP) and the authentication of users via SIM cards. The technology described in UMTS is sometimes also referred to as Freedom of Mobile Multimedia Access (FOMA) or 3GSM.

HSPA+, or Evolved High-Speed Packet Access, is a technical standard for wireless, broadband telecommunication. HSPA+ enhances the widely used WCDMA based 3G networks with higher speeds for the end user that are comparable to the newer LTE  networks. HSPA+ was first defined in the technical standard 3GPP release 7 and expanded further in later releases.

HSPA+ provides an evolution of High Speed Packet Access High Speed Packet Access provides data rates up to 168 Megabits per second (Mbit/s) to the mobile device and 22 Mbit/s from the mobile device.