Racism = A baseless prejudice against a community or individual on the grounds of their colour.
Islamaphobia Break it down into two words Islam a religion. Phobia a fear. The phobia part isn't entirely baseless given there have been numerous attacks worldwide with thousands upon thousands of fatalities. Most atrocities are aimed at random people in varying scenarios, as they were when the IRA had their campaign on mainland Britain, many of us had phobias about them. I had only been in the US for a day in 2006 when the aborted transatlantic aircraft plots emanating from Britain were discovered, from that stemmed the banning of liquid in hand luggage. It changed the nature of how we all had to check in. Of course people were paranoid after that which is pretty much the same as having a phobia, if all the intended explosives had been detonated imagine the loss of life, not as great as The Twin Towers, but pretty substantial. To summarise, I have a phobia, in such situations, dress it up how you like, I'm phobic about the people who carry out such attacks and where or whether they may occur again. Since 2001, most atrocities resulting in mass murder have been carried out by radicalised Muslims. Before that on British soil, mass murder as acts of terrorism were committed by the IRA, and therefore I assume Irish. if I lived in the US I'd no doubt have gunaphobia, perpetrators, any old Tom, Dick or Harry who has a grievance .
Phobias therefore tend to manifest against Islamist extremists, but not Muslims per se.
The IRA but not the Irish as a race
Any Old Tom, Dick or Harry with a gun and a grievance in the US but not the American people
Phobias surrounding traumatising events aren't really irrational, especially in areas where umpteen people packed together have been maimed and killed at the hands of terrorists whatever their cause.