These 4 kinds of agents, mainly in the proxy server-side configuration is different, causing it to send requests to the target address, REMOTE_ADDR, http_via,http_x_forwarded_for three variables different.
1. Transparent proxy (transparent proxy) remote_addr = proxy IP http_via = proxy ip http_x_forwarded_for = Your IP
Transparent agent Although you can "hide" your IP address, but still can be from http_x_forwarded_for to find out who you are.
2. Anonymous proxy (Anonymous proxy) remote_addr = proxy IP http_via = proxy IP http_x_forwarded_for = proxy IP
Anonymous agents have improved a little more than transparent proxies: Others can only know that you use the agent, do not know who you are.
There is a bit more advanced than pure anonymous proxies: confusing proxies, see the next section.
3, confusion agent (distorting proxies)
REMOTE_ADDR = Proxy IP
Http_via = Proxy IP
Http_x_forwarded_for = Random IP Address
As above, and the same as anonymous agent, if you use a confusing agent, others can still know you are using the agent, but will get a fake IP address, disguised more lifelike:-)
4, High stealth agent (Elite proxy or higher anonymity proxy) remote_addr = proxy IP Http_via = not determined http_x_forwarded_for = not deter Mined
Can be seen, high hide agent so that others can not find you are in the use of agents, so is the best choice.