The first thing all mean the same thing. Which is using IP 
(Internet protocol) for voice services. Some voice networks 
are only packet-switched and have no access outside of 
their own VoIP network. Most VoIP networks have a Gateway 
that connects to a circuit-switched external network which 
gives them acces to external calling. One of the gateways 
responsibilites is to convert G.711 Circuit-switched media 
(typically a T1 provided by a telco company) to the 7.723 
Packet-switched media that will traverse the companies VoIP 
network. A device called a gatekeeper will then convert the 
IP address (used by H.323 protocol) to a standard telephone 
number (E.164 address) that can be used for external 
calling.  

A converged network is a network that passes both Voice and 
Data over the same set of devices. Converged networks 
generally implement QoS (Quality of service) on all actived 
network devices to ensure the VoIP has priority over 
standard data because of it's more rigid demands.

voice over internet protocol, also called voip,ip 
telephony,broadband telephony,broadband phone 7 voice over 
broad band is the routing of voice conservations over the 
internet or through any other ip-based network.voip 
services convert into a digital signal is converted to a 
regular telephone signal before it reches the destination.

VoIP (Voice over Internet Protocol) is simply the
transmission of voice traffic over IP-based networks.

The Internet Protocol (IP) was originally designed for data
networking. The success of IP in becoming a world standard
for data networking has led to its adaption to voice networking.

VOIP means voice over internet protocol. In which the voice is send through internet (or any IP network). For that the analog voice is converted into digital 
data and use appropriate CODEC (for bandwidth saving) and send through IP 
network. At the receiving end the digital data is converted back into analog 
voice.

Short for port-switching hub, a special type of hub that 
forwards packets to the appropriate port based on the 
packet's address. Conventional hubs simply rebroadcast 
every packet to every port. Since switching hubs forward 
each packet only to the required port, they provide much 
better performance. Most switching hubs also support load 
balancing, so that ports are dynamically reassigned to 
different LAN segments based on traffic patterns. 
Some newer switching hubs support both traditional Ethernet 
(10 Mbps) and Fast Ethernet (100 Mbps) ports. This enables 
the administrator to establish a dedicated, Fast Ethernet 
channel for high-traffic devices such as servers.

Application layer
Presentation layer
Session layer
Transport layer
Network layer - Routers
Datalink layer - Switches
Physical layer - Hub

router operates at network layer

PHYSICAL LAYER-HUB

DATA LINK LAYER_SWITCH

NETWORK LAYER-ROUTER

TRASPORT LAYER-GATEWAY

A multicast router discriminates between multicast and 
unicast packets and informs switching devices what to do 
with the multicast packet.

A hub is prone to collisions as pc's connected to a hub 
form a single collision domain.
Where as in a switch each port is a collision domain and 
the bandwith of each port is fully utilized.
Each port is  a collision domain in a swith.

A hub is prone to collisions as pc's connected to a hub 
form a single collision domain.
Where as in a switch each port is a collision domain and 
the bandwith of each port is fully utilized.
Each port is  a collision domain in a swith.

hub works on physical layer and hub do not break up 
broadcast domain and do not break up collision domain.

switch works on DataLink layer and it break up collision 
domain but do not break up broadcast domain .

Router works on network layer and router break up both 
collision and broadcast domain .

Hub is a multiport repeator. Works at the Physical layer.

Switch switches frames from one port to another. Works at 
the Data Link Layer.

Router is a device which is used to connect two different 
networks together. It works at the Network Layer.

Ultra Wideband or UWB is a technique based on transmitting 
very-short-duration pulses, often of duration of only 
nanoseconds or less, whereby the occupied bandwidth goes to 
very large values. This allows it to deliver data rates in 
excess of 100 Mbit/s, while using a small amount of power

Applications 

Build a home theater environment without cables 

Share live multimedia content between televisions 

Instantaneously transfer the images from a digital camera 
to another product

Lots of difference are there,...
most important&explicit are  spellings.