Boxing is the middle range for Muay thai. At this one range the boxer might have an advantage...exept that every thing the boxer does the MT guy should be able to do and counter from this range as well. The MT guy would also throw flying knees and some kicks from this range as well.

Close range is in the clench, knees and elbows, and devastating throws involveing throwing the person around by the head. ( and strecthing or even breaking the neck if they fight it )

I personally doubt that a boxer would stand much chance vs a thai fighter with the same level of trainning. His only chance would be a quick K.O. before the other guy got on his game.
Mitakuye Oyasin "We are all related"