What makes this Myanmar coup different

Very recommendable! Myanmar is a much more open and democratic country now than it was in 1988! The military today is very different from 1988.

"... Unlike 1988, the latest coup is not intended to change the political system but rather to change the government. Its leaders have carefully positioned the takeover within the framework of the 2008 constitution and they assure people that they’ll return power to an elected government after fresh elections. The constitution says that has to happen within two to three years, depending on the process. ... 

The coup leaders, however, have serious grievances against Aung San Suu Kyi, whose enormous popularity and renowned obstinacy ultimately upset the fragile power-sharing system undergirding the post-2011 reforms. ..."

What makes this Myanmar coup different | The Strategist The dominant response to the military coup in Myanmar on 1 February has been, ‘Here we go again.’ Media commentary has highlighted the strong similarities between recent events and the 1988 coup, explained by the supposedly incorrigible and unrepentant nature of the military (the Tatmadaw). ... 

However, we must recognise that, rather than being a replay of 1988, the 2021 coup is in fact a different type of coup by a different kind of military at a different point in world time—and it requires a different international response.