(Edit- long, apologies.)
My, how very condescending of you to all concerned.
And telling. I had hoped for better.
While I may not be a technical scholar of the crusades, I do know a thing or two about Islam (which is more than you demonstrate in your own short glance, above.)
If you are proposing that the term "holy war" means jihad, I must counter-propose that you are simply wrong. And ignorant of the true meaning of the word "jihad". (It is important to note that Mr. Hughes, whom you cite above, wrote said treatise in 1895, at a time when the Western understanding of the cultures and varying sects that comprise Islam, even the language, may not have been everything that it is today. I might suggest a scholar from a more recent century.)
By definition, by simply looking at the term itself, a holy war is any war that is "holy" (ie, religious), by being tied to a religious cause or impetus. So, if a war is started by a Pope (ie, a Christian), then you have a Christian Holy War. If started by Haile Selassie, you could (I suppose), have a Rastafarian Holy War, and so on. (If started by Christian politicians in the name of Christianity, actually politics aside, then likewise, at least in name if not in fact. There were political considerations that undermine the "holy" aspect of some of the crusades, no doubt.)
The term "Crusade" has inescapably christian overtones of the latin root "crux" (cross) in it, and so while a crusade in this sense may be a strictly Christian holy war, other than that you, as yet, have not made any distinction as far as I can see, between a Crusade and a Holy War. The latter merely is a more general, non-specifically christian term. (Tho' the 12 lines of latin were pretty.)
If you believe the term "Crusade" has certain connotations that set it apart from a generic Christian holy war (or others'), other than the bureaucracy of the papacy, do feel free to suggest them. If your point was that there is a difference between the historical Christian Crusades and an Islamic call to Jihad, that would be a given.
btw-
Despite Mr. Hughes' 19th century opining, while a holy war is not necessarily a jihad, nor is every jihad a holy war. (Hughes does touch on this, but only in passing.) The term "Jihad" literally means "struggle", altho' "fighting" or "warring" are also possible translations, as they are its synonyms in English - it's not a 1:1 sort of relationship. (And I question whether his translations took this into account. Many of those I've heard referring to the daily "struggle" against temptation, not warring on non-believers.)
When Islam was first codified, there were laid down 5 pillars, 5 basic tenets that comprised the essence of being a Muslim. They were 1) a Declaration that Allah was God, 2) Prayer, 3) gving of Alms, 4) Fasting (during Ramadan), and 5) a pilgrimage to Mecca. There was debate on a 6th, Jihad, but it was deemed non-central - important, but not critical.
To "jihad" is to struggle against anything that would prohibit one from being Muslim- day to day temptations being foremost. However, if a foreign power were to try to take away wealth from your country, or dictate how you should worship, then a general call to a collective Jihad, a more formal "struggle" against that country, could form a Holy War, and that would also be called a Jihad. The difference is a crusade against cancer, and the sort of crusade called by Pope Innocent III*.
It's also important to note that, unlike Christianity, not only does Islam not promote prostilization, it specifically prohibits it. Christians have historically been happy to go to war to force others to convert- Islam (since the days of the Prophet himself) traditionally goes to war to prevent others from converting them.
But both Jihads (in this sense) and Crusades (in the same sense) are holy wars, by any other name, just as they both can be struggles, in the less military sense. The difference is that in Christianity, the term started out militaristic, and we adopted a more analagous secondary meaning, and in Islam, the term started out general, and only in modern times became (to some) synonymous with holy war.
It's also important to note that Islam does not have a single "authority", no person nor body, that decrees doctrine for all true believers. It does have a hierarchy of men (yes, always male, ahem) who are learned and recognized for their wisdom- the Ayatollahs, and Imams (lesser), but while they can preach, and can demand and pass personal judgement, they have no more authority than the number of Muslims who listen to them give them. So, if one declares "jihad" against someone, while their followers might answer the call, the vast majority might just roll their eyes at another koran-thumpin' trouble maker.

(* As a modern linguistic note, when Pres Bush called for "a crusade against the evil of Saddam Hussein", while English speakers may have heard the first meaning, of a general struggle, Islamic speakers heard only the "crux" echoed, the holy war of Christian against Muslim. Years of practice.)