The huge difference being that the Packers could release both Smiths after only two years and save a total of $57 million in cap space until 2022 if they don't perform up to expectations. The Bears don't have that option with Mack.
That lowers the risk significantly.
You don't even have to go out to 2022 to see the contrast. The contrasts begin now and continue to skew in the Packers favor from there.
After 2019:
The Smiths: $27 mil dead cap, $3.75 mil cap savings
The Smiths + Amos + Turner: $42 mil dead cap, $5.75 mil cap savings
Mack: $44.1 mil in dead cap,
negative $17.5 mil cap savings
After 2020:
The Smiths: $18 mil dead cap, $18.75 cap savings
The Smiths + Amos + Turner: $28 mil dead cap, $26.75 cap savings
Mack: $21.4 mil dead cap, $5.25 mil cap savings
While no one would expect the Packer acquisitions to be worth less than those very modest cap savings in 2020, by 2021 the cap savings among these players are meaningful-to-significant. Stuff can happen, a losing record requiring more retooling, an underperforming player from injury or otherwise, a major suspension or a clubhouse disruptor, where cutting bait might be called for. We do not expect it, and it wouldn't be all 4 of those players, but stuff does happen. What would Mack have to do to be cut going into 2021 with that dead cap and small savings? Sex change operation?
That touches on an underappreciated aspect of the two scenarios: the Packers diversification thereby reducing risk. If Mack blows an ACL , their plan for 2019 is shot to h*ll, worse in 2020 where they'd be sitting on Mack's $26.6 mil cap cost with no player. Similar risks spread across four players sharply diminishes overall risk.
Then there are the two first round picks.