Hi, I was just wondering what the difference is between Status internal identifier and Name status tag under the Personalised Status tab?

The 'Internal Identifier' is what the server says your status is.
The 'Name Status' tag is appended to your name, and Plus reports this as your status.
Actually, Tochjo (below) is correct.

A status internal identifier is a name you can give to a certain combination of personal status and away message.

The name status is what will be visible as status to people who have Plus!, and visible in your name to people who don't have Plus!.

When you set your status to Away in the contact list (click the name and choose Away), you can type a Name status tag in the box. When you set your status to Away, and use Fishing as your personalised status, people with Plus! will see your name as
Name (Fishing)
with an away indicating image in front of it.

People without Plus! will see your name as
Name {Fishing} (Away)
with an away indicating image in front of it.

As mentioned before, with the status internal identifier you can give a name to a certain combination of personal status and away message. When you click the button Presets in the pop up window shown when you set your status to away, you will see a list of those status internal identifiers.

By clicking one from the list, the settings for that status internal identier will be used, as saved in the Preferences (i.e. your name status tag and your away message for that status internal identier).

Summarising:
- name status tag is the custom status you enter
- status internal identifier is the name for the 'group' containing the name status tag and away message associated to it. You can set these groups in the Preferences.

I hope you understand it now

Thanks!