Difference between HTML, URL Mode Recording in Load runner

HTML Mode:

• Default and recommended recording mode.
• Records HTML action in the context of the current Web page so that all we see on a web page will be
   recorded in a single function which makes it easier to read.
• Advantage of this mode is that it generates a script that is intuitive to the reader in terms of what is
  the form requesting (in a form of entire web page).
• Best for browser applications.

URL Mode:

• Instructs VuGen to record all requests and resources from the server. It automatically records
  every HTTP resource as URL steps.
• Generates a script that has all known resources downloaded for your viewing which works good
  with non-HTML applications such as applets and non-browser applications (e.g. Win32 executables).
• Having everything together creates another problem of overwhelming low-level information and
   making the script unintuitive. Difficult to read.
• When there are unrecognizable requests made to the server in Web (HTTP/HTML) protocol, they
   are recorded as web_custom_request. However, in URL-mode, this can be selected to allow
   recording to default to web_custom_request.

GUI Mode:

• Introduced with Web (Click & Script) protocol.
• GUI-mode option instructs VuGen to record all editable fields in an object or non-browser
  applications. What it does is to detect the fields that have been edited and generate the scripts
  accordingly.
• Concept similar to functional testing when objects are detected at theGUI-level. When reading the
  script, it allows easier reading as the script is based on the GUI presented to the real user. Easier to
  read in context of the object.
• Best for applets and non-browser applications.