I'm looking at the character archetypes and I noticed that the Gadgeteer archetype has the "Precise" modifier on their Protection power. Does it make it different to other Sustained Protection powers?
You can use a Precise effect to perform tasks requiring delicacy and fine control, such as using Precise Damage to spot-weld or carve your initials, Precise Move Object to type or pick a lock, Precise Environment to match a particular temperature exactly, and so forth. The GM has final say as to what tasks can be performed with a Precise effect and may require an ability, skill, or power check to determine the degree of precision with any given task.
With Precise, the character can turn off parts of his Protection while still leaving most of it on - perfect for medical treatments while under fire. The character can also "tune" his force field - whatever that means.
Some concrete examples would include adjusting the force field to "phase match" another energy field - allowing the Gadgeteer to pass through safely and unharmed (an example of descriptor based countering, enabled by Precise) - or "adjusting the field" to allow medical lasers to provide surgical treatment while still protecting the character from enemy blaster attacks, or "shaping the field" to a wedge-like shape to maximize cover on the bystander the character Interposed for (making the charging monster sail over the target).
The player's creativity and the GM's allowance are the real limits on what Precise can do.