In act, after you add all of Bush's active duty days together, you come very, very close to the amount of time that Kerry actually served.
Especially considering that Kerry requested an EARLY DISCHARGE from his "admiral aide" position to run for Congress!
After leaving his first ship months early to get transferred to "easy" duty off-shore in swift boats.
Then leaving the swift boat duty after only a few weeks duty when they began fighting inshore on the rivers. Kerry got administratively transferred home (after viciously complaining to both Abrams and Zumwalt) because he claimed (on an unwritten technicality!) that he could demand to leave Vietnam because of 3 "non-treated", minor wounds.
1966
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Graduates from Yale.
February 18: Kerry enlists in the US Navy.
October 19: Kerry is ordered into active duty.
December 16: Kerry receives his Navy commission, a few days after his 23rd birthday.
1967
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Kerry spends the year in military training.
December: Kerry begins his first tour of duty, serving on the guided-missile frigate USS Gridley.
1968
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February: With Kerry aboard, the Gridley sails into war to patrol the coast of Vietnam. He never came into contact with the enemy during this time.
June 6: Kerry's first tour ends as the Gridley returns home.
December: Begins second tour of duty as the skipper of swift boat No. 44, patrolling the Mekong Delta in southern Vietnam.
1969
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February 28: Kerry shoots and kills a Viet Cong guerilla who was threatening the lives of Kerry's crew. He received the Silver Star for his action.
April: Kerry ends his second and final tour in Vietnam.
1970
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January 3: Discharged from the Navy.
February: Kerry gives up on his first bid for office as a protest candidate in the race for the Third Congressional district.
http://www.boston.com/globe/nation/packages/kerry/timeline.htm Also Kerry's tours in VN were quite short by normal standards. His first was three months. His second three and a half months.
And as you say, he got of out the Navy early to run for Congress. But in fact, he didn't run. He didn't even enter the primaries.