First, Unit Stats, base wargear, special rules, and unit cost:
Angels of Death
Unit Cost: 170 (Heavy Support)
Stats:
WS BS S FA SA RA I A HP
5 5 7 13 12 10 4 4 3
Wargear:
Multi-Melta
Power fist with built-in Combi-bolter
Atomantic Shielding
Special Rules:
Chapter Tactics
Fleet
Forge World Imperial Armor
Unit Cost: 175 (Elite)
Stats:
WS BS S FA SA RA I A HP
5 4 7 13 12 10 4 2 3
Wargear:
Twin-linked Heavy Bolter
Dreadnought close combat weapon with built-in Storm Bolter
Atomantic Shielding
Searchlight
Special Rules:
Fleet
As you can see the Angels of Death version has a higher BS, more attacks, and a slightly lower cost.
The next discussion point is the options.
For AoD, you have two options:
1) You can add up to two more Contemptors to the unit for 170 points each
2) You can swap the multi-melta for a Kheres pattern Assault Cannon for 15 points.
For IA, there are several options:
1) You can swap the Heavy bolter for a multi-melta (free), twin-linked autocannon (+5 points), plasma cannon (+10 points), Kheres pattern assault cannon (+15 points), Twin-linked lascannon (+25 points), heavy conversion beamer (+35 points), or a dreadnought close combat weapon with built-in stormbolter (free).
2) You can swap the dreadnought close combat weapon for a chainfist with built-in stormbolter (+10 points), multi-melta (free), Twin-linked autocannon (+10 points), Plasma Cannon (+10 points), Kheres pattern assault cannon (+15 points), Twin-linked lascannon (+25 points)
3) You can swap the storm bolters for the following: Heavy Flamer (+10 points), Plasma blaster (+20 points), graviton gun (+15 points), or a meltagun (+15 points)
4) You can add the following: Extra Armor (+10 points), Targeting Augury (+15 points), or a carapace-mounted cyclone missile launcher (+15)
As you can see the IA version has more options, but cost more overall. For example, the IA version with a multi-melta and BS 5 costs 190 points (175 base, +15 points for Targeting Augury), and it would still have 2 less attacks.
