Both of these patterns are used for the same thing: squeezing a lot of content into a limited area of a (web) page. Although they can save a lot of space, the content you insert using them is limited to an amount by the size of the area you’re filling. Which is better? The one which suits your needs, let’s take them one by one:
TABS:
Tabs are one of the patterns known by about everyone. Designed well, they don’t make any problems to the user. The first use of tabs (I think) was the paper folders filing systems used in cabinets.
Advantages:
- very familiar to users
- easy to use
- the height of the tabs area can be unlimited
Disadvantages:
- tabs don’t work with long tab names
- they don’t do well in tight spaces either
- 2 tab bars is not an option so you are limited to a relatively small number of tabs
COLLAPSIBLE PANELS:
A little tricky to use for beginner users, but still quite intuitive and sort of familiar (used in desktop applications and operating systems). Make sure they have a “collapsible hint” like “+/-” or a down arrow like this:
Advantages:
- work well long names (as long as the width of the area)
- you can open two at the same time (if they are build that way and you afford the space)
- work well in tight spaces
Disadvantages:
- height consuming
- less obvious than tabs
- they look silly if used on full width
- it’s easier to mess their design and get a usability fail
Let’s face it! People use the same passwords on every site where they need an account. More exactly their email and computer login password You’ll be amazed how many of the users have only one password. It’s a bad thing but that’s how it is.
A while ago a friend of mine wrote on his blog about sites which demand a certain number of chars, demand to use both numbers and letters and even one of the weird signs on the number keys. Putting a maximum limit on the number of chars is plain stupid.
Please! don’t make users come up with a different password than they already use. Chances are they already use a password with more than 6 chars (due to restrictions allover the place). If you make the user invent a password with #$%^, he’s going to forget it. Then, he would have to recover/reset it – things that generates errors and frustration.
I’m happy to show you a project that won the DevWorld Award the other day. The project is an Interactive Wireframes and Software Prototypes app. The soft is pretty neat, it’s a very good tool for wireframing and UI mockup. Here’s what i’ve done in 2 minutes:
You’ll be amazed how many of the users have only one password. It’s a bad thing but that’s how it is. 
