Built-in Special Summons (also known as inherent Special Summons) are Special Summons that happen due to a condition that the monster has; this Special Summon does not start a Chain. This can only be performed when the game state is open during your Main Phase (for example, "Cyber Dragon", "Solar Wind Jammer", "Ghost Ship", "Exodius the Ultimate Forbidden Lord", etc.). This type of Special Summon behaves similarly to Normal Summons and Flip Summons. Contact Fusions, Synchro Summons and Xyz Summons fall into this group of Special Summons.
http://yugioh.wikia.com/wiki/Special_Summon
So Roach can negate all these things.
And the reason it can't negate Special Summons via card effect is because once an effect has started resolving, it cannot be interrupted. This means that in order to prevent the summon, the only option is to negate
the card effect itself. In order to be able to do that, the counter-card's text has to include the following wording:
"When a monster would be Summoned,
OR when a Spell Card, Trap Card, or monster effect is activated that includes an effect that Special Summons a monster(s): Pay 2000 Life Points; negate the Summon
or activation, and if you do, destroy that card." (courtesy of Solemn Warning)
If that second part is not present in a card's text (as in the case of Steelswarm Roach), you cannot use it to prevent a Special Summon of a monster via another card's effect.
Another similar wording you might encounter:
"Negate the Special Summon of a monster,
or the effect of a card that would Special Summon a monster."