yes, KKg = metric ton = 2204.6 lb. The US incidents are given in English tons, so I converted for the same basis. (Mt could be mega-ton and mt milli-ton, so it's tricky to know how to abbreviate).
Interested parties can find lots of information on AN hazards and explosive effects in the US Chemical Safety Board's final report on the West Fertilizer plant accident. (The CSB has put out reams of information generally valuable to industry and society over the years, but is currently being starved of funding and leadership to passively close it down- but I digress into editorial). Also note that this- and the Tianjin accidents were both contemporary with the storage period of this material in Beirut. The Texas City accident was the largest (non-redacted) accident in terms of AN in the CSB survey, giving Beirut the new dubious distinction on that count.
Of course there's myriad factors that affect relative severity of the four disasters. Still, the quite sizable explosion from the Waco incident from a _comparatively_ small amount of material makes me wonder if the explosive force scales non-linearly with the amount of AN?