How do you distinguish between what is real and not real Jihad?

For common person it is not easy. It is better for a layman not to dwell into this matter. It is best for the scholars to decide upon it. Is suicide bombing considered Jihad? No, as a practice it is not considered that, when people strap bombs and go into public areas and blow themselves up, this is not Jihad. However in battlefield, a suicide mission is known in the realm of a military tactic. A given circumstance may call for it. As a general practice, it is haram; suicide is haram.

Thabit b. Dahhak radiAllahu anhu reported that he pledged allegiance to the Messenger of Allah (ﷺ)  under the Tree, and verily the Messenger of Allah (ﷺ) observed:

Prophet (ﷺ) said: “He who took an oath of a religion other than Islam, in the state of being a liar, would become so, as he professed. He who killed himself with a thing would be tormented on the Day of Resurrection with that very thing. One is not obliged to offer votive offering of a thing which is not in his possession.” [1]

Something like this is serious, and is haram whether it is euthanasia. One blows himself up to blow up others he is upset with, this is strictly impermissible. This is not from Islam and it is not Jihad.

Reference:

[1] Muslim, Book 1, Hadith 208.