Disclaimer: I'm not a PHP or Ruby programmer. I come from the land of Java and Python.
@posts = Post.where(:status => 'public').order('created DESC')
$records = $this->_model->blogs->fetchAll(array('status = ?' => 'public'), 'created DESC');
Assuming these would be returned from a framework library, or I can't readily access the source and this is just part of documentation.
The first example is fairly readable, concise and sensible. Knowing a little about how Ruby handles things as objects, I "get it" and am comfortable with what @posts would probably contain. I'm fairly certain @posts is a plural set/object of more Post objects, which represents a row in a database, where status is public, then ordered descending. I can probably iterate through it. As an outsider, I could read this, lookup the column names for the row and almost immediately start using it.
Knowing some of the problems with PHP and its community, I can make no assumptions about what $records will really be unless I know the author's style or am already familiar with the codebase. Ignoring your writeup justification for shortening, I can't guess what _model is, I don't know what blogs really represents, and I'm uncertain why fetchAll needs an array object passed as a parameter, I have to mentally replace the question mark with "public", then assume the second parameter is an order-by parameter since I see the DESC. Before I would be ready and comfortable to use $records in a meaningful way, I'd have to dump it to the screen or use a debugger, plus lookup the syntax for fetchAll, and I'd really want to know what _model and blog actually represented since you're now magically assuming the blog object links to a table somehow. I do not know if blog is iterable or if it's rows it has grabbed are even accessible. $records may be the result of some manipulation it performs on the query result. I just don't know, and that makes me uncomfortable.
So while you've reduced character quantity to near comparable levels, you've not matched readability or understanding. You've merely condensed complex code into short complex code. Honestly, I think it's a philosophy difference between PHP and Ruby. Ruby the language strives for the principle of least surprises, and if the programmers utilizing it adhere to that, I can grasp their code pretty quickly. PHP is a grab-bag; you can make no assumptions, which is both a strength and a weakness.
Granted, PHP can still be used successfully to start and run a business, but as a programmer with no professional experience in either language, I'm gravitated towards the Ruby example.