I often find academics with tenured bracketed beside their position. What is meant by a tenured position? Is this different from a permanent teaching position?
In short, tenure means that you cannot be fired (you have a very permanent position). For more details, look at this question: In practice, how secure is a tenured position in the US? In particular, look at the first link in the first answer to that question, which is an article in Science that talks about the role of tenure.
To have tenure is an acknowledgement from the host institution of the academic's record of published research, teaching and contribution to the administrative life of their department/institute/college.
It is difficult, but not impossible, to fire a tenured academic from their host institution. See e.g. http://www.hr.msu.edu/documents/facacadhandbooks/facultyhandbook/dismissal.htm
An academic with tenure is typically only dismissable on very serious grounds of misconduct. That it is so difficult to dismiss a tenured academic arises, historically, from the idea that university researchers should enjoy academic freedom - the ability to research unfavourable topics, persue and advance unpopular or controversial theories, to challenge the status quo without fear of reprisal in the form of dismissal.
The tenure system is itself, somewhat controversial, see e.g. http://www.mindingthecampus.com/originals/2012/07/how_to_save_tenurecut_it_way_b.html
The implementation is a tenure contract, which specifies a starting salary, starting date, and often a maximum duration (e.g. 30 years). Other possible details include startup funds (e.g. US$1M over 10 years), lab space (dry/wet lab, exclusive use square footage), and access to shared facilities (big experimental equipment). Lab space and shared facilities aren't free, so the cost is often deducted from your startup funds.
There may be requirements in the contract about the maximum number of days you can spend off-campus doing consulting work, the minimum amount of lab activity required to be considered active (papers per year, grants submitted/funded per year, students trained per year), minimum service work (hours spent on committees, hours spent writing policy documents), and minimum teaching commitment.
If you fail to meet the minimums, your department may start to revoke some of your privileges. You may wish to read this other question about enforcement of the policies.
There's a wide variation between different universities and departments about what gets written in the contract and what is actually required due to departmental politics. The political part of the equation can be a lot more important than the text in the contract on a day-to-day basis. Consider what could happen if the department runs out of lab space or if you have trouble getting new grant funding for a couple years.