In other words, on the evidence so far, one case was a coverup and the other is still a mystery.
It is also well-documented that Al Quaida ops experimented with improvised explosives. They killed a Japanese businessman and nearly crashed the whole plane in that case. Plus we have the recent shoe bomber. This flight was on its way to the Dominican Republic, and would have been carrying lots of very random stuff like small appliances and electronics for the folks back home. It would also be fairly easy for an African Moslem to pass for a Dominican (there were no obvious Moslems on the passenger list). Plus there is the timing (UNGA in town, Bush the day before)and location - almost within sight of the UN building and Ground Zero.
Then there is the direct evidence of coverup. Numerous bogus "explanations" were placed with the press, among them: Old engine (proved wrong), bird strike (proved wrong), wake turbulence (proved wrong), cheese (still in play), thrust reversers (proved wrong). The cheap French plastic tail theory is literally the "center fuel tank explosion" of this crash: No other plane was grounded because of this theory.
It may be a mystery, but when you have an explicit threat against airliners by terrorists, the likeliest solution is the one that came out and said "We will cause more airliner crashes."