Assuming the amsmath package is installed. I found a difference between the way that an equation object and a gather object is embedded within the text.
If an equation is beneath a line of text that does not extend as far to the right as the equation. Then the equation is placed higher up for asphetic reasons like so:
Hello there this is some text, blah, blah,
blah, blah
a+b=c
Some more text, hello
Or if the text goes beyond the equation, like so:
Hello there this is some text, blah, blah,
blah, blah, blah, blah
a+b=c
Some more text, hello
If gather is used, then the gather object is placed a certain distance beneath the last line of text, regardless of it's extent across the page.
I would like gather to align equations in the same way as equation objects but this isn't as simple as using a permanent vspace{} command to push text up as it's need will be depend on the final layout of the text.
Can any one help? maybe this is even a bug to be resolved. by the ams group.
Thanks
I have prepared an example latex document here: http://pastebin.com/EUKyNi2A