TRACK DEV DEPARTING LA MESA; HONDURAS; WHEN FMS RTE DOES NOT MATCH ICAO CLRED RTE. THE FULL READBACK OF THE FMS LOADED RTE; WHICH WAS IN ERROR; WAS NOT CAUGHT BY CLRNC DELIVERY.

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FLT PAPERS ARRIVED WITH A NOTE ABOUT A CHANGE TO THE RTE. AFTER A SHORT DISCUSSION; WE COMPARED THE ACARS UPLINKED RTE TO THE RTE ON THE FLT PLAN. HOWEVER; DURING THIS DISCUSSION; WE WERE DISTR WITH A WT AND BAL ISSUE THAT TOOK OUR ATTN AWAY FROM COMPARING THE RTES PREVIOUSLY DISCUSSED TO THE RTE ON THE ICAO FLT PLAN FORM. AS WE TAXIED OUT FOR TKOF; WE CALLED FOR AND RECEIVED OUR IFR CLRNC FROM LMS (SAN PEDRO SULA; HONDURAS) TO HOUSTON; TX. THIS IS STANDARD PRACTICE IN THIS PART OF THE COUNTRY. THEY CLRED US 'AS FILED' AND THE FO READ BACK THE WHOLE CLRNC INCLUDING THE 'RTE' WE HAD ON OUR FLT PLAN AND IN OUR COMPUTER. THE CTLR NEVER QUESTIONED THE FO'S READBACK. AFTER OUR TKOF; WE WERE CLRED TO JOIN THE AIRWAY ON COURSE. A FEW MINS INTO THE FLT; THE DEP CTLR QUESTIONED OUR HDG/COURSE; AND WE ADVISED HIM THAT WE WERE ESTABLISHED ON THE 347 DEG RADIAL OF LMS. THE CTLR TURNED US TO A DIFFERENT HDG AND ASKED US ABOUT OUR RTE. WE AGAIN ADVISED HIM OF OUR RTE THAT WE THOUGHT WE WERE CLRED ON. WE DISCOVERED AFTER FURTHER REVIEW THAT THERE WAS A DIFFERENT DEP SEGMENT ON THE ICAO FLT PLAN THAT CONFLICTED WITH THE ACARS UP LINKED RTE; AS WELL AS THE FLT PLAN RTE. FROM THIS POINT ON; THE CTLR JUST GAVE US A CLRNC BACK ONTO OUR ORIGINAL RTE AND THERE WAS NO FURTHER DISCUSSION. AS A CREW; WE SHOULD HAVE PAID MORE ATTN TO THE COMPARISON OF ALL RTES; AND WE COULD HAVE AVOIDED A LOT OF CONFUSION BY REQUESTING A FULL CLRNC READBACK. PDC'S ARE VERY COMMON IN THE UNITED STATES; HOWEVER; NOT IN OTHER COUNTRIES. WE ALSO LET WT AND BAL ISSUES INTERRUPT THE TASK AT HAND; AND WE SHOULD HAVE BEEN PAYING A LITTLE MORE ATTN TO THE RTE CONFLICT.