Same average service time. Watch what variability does.

Deterministic

zero variance
Now
0
Avg
0.0
Max
0

Exponential

classic M/M/1
Now
0
Avg
0.0
Max
0

Heavy-tailed

rare slow customers
Now
0
Avg
0.0
Max
0
λ (arrival rate)0.80
μ (mean service rate)1.00