Difference between function names from Drupal Devel
Maybe this can help you a bit:


dpm($var) or dsm($var) - displays the information about a variable in the form of system messages using Krumo.
dvm($var) - displays the information about a variable in the form of system messages using var_dump($var).
dpr($var, $return = false) - displays the information about a variable at the top of the page, using print_r($var, $return).
dvr($var, $return = false) - displays information about a variable at the top of the page, using var_dump($var, $return).
kpr($var, $return = false) - displays the information about a variable at the top of the page using Krumo.
dargs() - displays information about the arguments of the current function at the top of the page using Krumo.
dd($var, $label = null) - writes the information about a variable in the file drupal_debug.txt, which is located in the temporary directory (admin/settings/file-system).
ddebug_backtrace() - displays the call stack at the top of the page using Krumo.
db_queryd($query, $args = array()) - this is a debug version of db_query(), which displays it at the top of the page after the execution of $query.
dpq($query, $return = FALSE, $name = NULL) - this is an analog to the function db_queryd() only available in Drupal 7. Outputs SQL query using dpm() with substituted arguments. The first parameter takes an object DBTNG.