u/Slay_the_PE

These are the things that are new to this edition. New items are shown in boldtype. If things are added to the handbook, it is reasonable to assume (in our opinion) that NCEES wants to use this stuff in upcoming editions of the exam.

TFS people should take note of the changes in Chapters 3, 4, and 5
HVAC people should take note of the (minimal) changes in Chapter 9
MDM people should take note of the changes in Chapter 2

1.8: Project Planning and Scheduling: It defines key project management terms: critical path, deliverables, dependencies (start-to-start, start-to-finish, etc.), float, Gantt chart, key performance indicators (KPIs), and lead time.
"Ductile Iron Pipe Dimensions", page 85. Supplements the existing schedule 40, 80, XX, and copper pipe data table.

2.5.8 Cable Subject to its own weight: Typos in the catenary curve equations were fixed.
2.14: Added the Goodman equivalent stress formula
2.15.2.1 Torsional Mass and Spring (Pendulum)
2.15.12: Compound Pendulum
2.15.13 Conical Pendulum
2.15.14 Floating Block
(Chapter 2 findings courtesy of u/benakamaverick)

3.4.2.10 Equivalent Lengths for Pipe Fittings (this new table replaces the old "Equivalent Length in Feet of Pipe for 90° Elbows" table)
3.4.2.13.The equations for gas pipe sizing presented after the capacity table changed. In the previous edition it was the ASHRAE equation. Now it is the equations from the International Fuel Gas Code.
3.4.3 Drainage Piping. This deals with flow in pipes that are not full of liquid, but rather have a free surface of water and there is air on top.
3.8.6 Fire Hydrant Orifice
3.9 Expansion or Compression Tanks​

4.5.2 The equations for isentropic expansion of an ideal gas with constant cp were added at the bottom of page 297 (Brayton cycle)
The block diagram for the air refrigeration cycle was replaced with something that is conceptually wrong. Air refrigeration uses a turbine (constant entropy in the ideal case) which produces power, but they now drew an “expansion device” which could be confused with a constant enthalpy device as in the vapor compression refrigeration cycle.

5.1.5. Critical Insulation Radius; now this concept gets a dedicated section but the equation was there before.
5.2 The conduction resistance for a plane wall is wrong. It is L/k, not L/(kA).
5.7 Adiabatic Mixing of Fluids

9.3.7.5 Minimum Ventilation Rates: The general notes for the table were deleted.
9.3.8.4 They fixed the typo in the equation for Pf; the fan shaft power required.
9.3.9.2 They re-wrote some of the equations, but nothing substantial changed.

Nothing major changed. They seem to have only added Section 1.8: Project Planning and Scheduling: It defines key project management terms: critical path, deliverables, dependencies (start-to-start, start-to-finish, etc.), float, Gantt chart, key performance indicators (KPIs), and lead time.

Also, there are a few more unit conversion factors in the conversions table.