Basic HTTP binding : In HTTP binding Data is sent as a plain text.In other words,there is no security provided for the message when the client calls happen. This is aimed for clients who do not have .NET 3.0 installed and it supports wider ranges of clients. Many of the clients like Windows 2000 still do not run .NET 3.0. So older version of .NET can consume this service. It uses SOAP1.1 version.
WS HTTP binding : As Ws HTTP Binding supports WS-*, it has WS-Security enabled by default. So the data is not sent in plain text. As its built using WS-* specifications, it does not support wider ranges of client and it cannot be consumed by older .NET version less than 3 version. It uses SOAP 1.2 and WS-Addressing specification