Render modes (Source 2)
These are all the rendering modes present in 
Source 2.
Confirm:Are there any significant changes to these in Source 2?Normal (kRenderNormal)
The default Render Mode.
Transparency keyvalues/inputs will have no effect on entities rendered with this mode.
Color (kRenderTransColor)
Behaves like the Normal Render Mode, but allows transparency.
Texture (kRenderTransTexture)
Same as color. Leftover from GoldSrc, where it would render as fullbright.
Glow (kRenderGlow)
Intended for glowing sprites. Allows transparency, and forces the sprite or model to be rendered unlit.
The size of a sprite rendered with Glow is consistent with the screen size (unlike the alternative World Space Glow), making it appear larger at a distance, in comparison to the world.
The GlowProxySize keyvalue affects this Render Mode on sprites.
Solid (kRenderTransAlpha)
Enables Alphatesting. Legacy port from Goldsource. Obsolete in Source due to Alphatesting being handled in materials. Does not allow translucency.
Additive (kRenderTransAdd)
Add the material's color values to the existing image, instead of performing a multiplication. Sprites will appear through world geometry and the sprite/model will always brighten the world. Allows transparency. Good for big sprites because it wont disappear near the edge of the screen.
Code: renderamt in this render mode is equivalent to a greyscale $color/$color2 on an $additive material; for example, a brush entity with rendermode 5 and renderamt 150 using an opaque material will look the same as a brush entity with rendermode 0 using a material with $additive 1 and $color "{150 150 150}".
Confirm:Is this true for Source 2?Additive Fractional Frame (kRenderTransAddFrameBlend)
Functions like Additive, but also blends between animation frames. Requires the material to have a functioning animating texture. Allows transparency.
World Space Glow (kRenderWorldGlow)
Functions similarly to Glow, with the exception that the size of the sprite is relative to the world rather than the screen.
The GlowProxySize keyvalue affects this Render Mode on sprites.
Don't Render (kRenderNone)
Also referred to as None.
The entity is still being drawn and networked albeit invisible, therefore not making this Render Mode ideal for performance reasons.
To completely avoid drawing and networking an entity, see EF_NODRAW.