There is no big difference between those functions except the syntax:
$(\'.target\').append(\'text\');
$(\'text\').appendTo(\'.target\');
A
Either way, it's fairly literal and i find myself writing each automatically without thinking.
In each context, if the subject is the area you are manipulating,
$(target).append(content)
//within a function based around manipulating a specific area
seems to make more sense whereas if the subject of the function is new content then
$(content).appendTo(target);
//appending data to something
makes more sense.
$(target).toggle().append(content);
makes more sense than adding another line and vice versa.
.append() (the jquery documentation)
.appendTo() (the jquery documentation)
a good blog post on the topic (see Difference between .append() and .appendTo() )