So this will be a pretty controversial post so bear with me...
https://www.ata-a.org.au/a-bad-day-in-the-bundestag/
TL;DR This article argues that the 'genocide scholar's researching the history of genocide are unfairly focusing on Armenian deaths even though number of Muslim deaths were roughly equal.
The resolution refers to the ‘almost complete extermination of the Armenians’ and the ‘pogroms’ against other Christians, namely the Assyrians and Chaldeans. In fact, hundreds of thousands of Armenians survived the war, in the Ottoman Empire and surrounding lands. The figure of one or 1.5 million ‘massacred’ is a double untruth because the true death toll was probably about 600,000, still a huge number, without any need of exaggeration.
And the most important part:
Furthermore, those who died were not all ‘massacred’: many were but by far the greater number died of exposure, disease or malnutrition or were killed in combat, the exact combination of causes which took the lives of about 2.5 million Ottoman Muslim civilians during the war. There is no mention in this resolution of the Muslim death toll or of the slaughter of Muslims by Armenians, especially when northeastern Anatolia was occupied by the Russians and their Armenian protégés between 1916-18. The archival evidence of survivors indicates that at least 500,000 Muslims were massacred between 1914-19.
My question is are these claims true and if so why is one only of them considered genocide and not the other?
Ok, so I am unable to give you information on the Armenian Genocide specifically as that is not my area of expertise. What I can tell you is that the arguments made in the article are standard fare for deniers of the Holocaust and other genocides.
In the first quote you give, note that the author attacks the genocide on the basis of numbers. In the case of the Armenian genocide, this is easy because the records kept by the Ottoman empire were not detailed. Hence, historians often cite different numbers of dead and in most cases, a range is given. However, whenever a group or author uses the higher of the range, a denier such as Salt will accuse that group of untruth. Note that he says, "the true death toll was probably about 600,000." He knows that there is debate among true historians about the numbers, but he chooses to depict the higher number as an outright lie.
The second quote you gave is clear diversion. None of it suggests that a genocide against the Armenians was not perpetrated. It only points to the numbers of of dead in the Muslim population during the war. He also accuses the Armenians of committing atrocities. This was the exact pretext used to initiate the Armenian genocide in the first place and now is used to deny it.
I hope that someone with better knowledge of this topic helps you out, but until then, know that the article does not give any evidence whatsoever that discredits the recognition that what happened in the Ottoman Empire between 1915 and 1918 (and beyond) was a genocide.