Here's my explanation. The calculator is supplied with a somewhat vague expression.
The first calculator interprets it as a fraction, the second calculator interprets it sequentially.
6÷2(1+2)
First calculator
What it sees
6_____
2(1+2)
Evaluate 1+2 = 3
Evaluate 2(3) = 6
Evaluate 6/6 = 1
Second calculator
What it sees
6 x (1+2)
2
Evaluate 1+2 = 3
Evaluate 6/2 = 3
Evaluate 3 x 3 = 9
Also lol canadians and "BEMDAS". It's PEMDAS because it has better mnemonics, such as "People Expect More ****s And Sex" (thank you xkcd)
Edit: had you punched in 6÷2*(1+2), the first calculator would have no trouble getting to the correct answer.
Evaluate 1+2 = 3
Evaluate 6/2 = 3
Evaluate 3 x 3 = 9