Roughly 95% of IBC totes in service in North America are HDPE bottles in a galvanized steel cage — what the industry calls "composite" IBCs. The HDPE is high-density polyethylene, blow-molded as one continuous piece with a built-in 6" threaded fill port and a 2" outlet. The plastic is chemically inert to most aqueous solutions, dilute acids, dilute caustics, vegetable oils, glycols, alcohols below 70%, and most water-miscible fertilizers. It is not friendly to aromatic solvents (toluene, xylene), chlorinated solvents, ketones, or anything that wants to soften it.
The steel cage is the load-bearing structure. The HDPE bottle, on its own, cannot support a stacked filled tote — the cage is what makes IBCs stackable two-high in warehouses and on flatbeds. Cages are typically 4–5mm tube stock, hot-dip galvanized, with welded crossbars on roughly 6" centers. Cage damage is the most common reason an otherwise serviceable tote gets retired.
Stainless IBCs are an entirely different animal. They run roughly 4–6× the price of composite, weigh nearly twice as much empty, and last effectively forever. 304 and 316L are the only two grades worth discussing for IBC use — see that page for the decision tree. There are also rotomolded poly IBCs (heavier-wall, cage-free) and stainless-jacketed composite hybrids, but neither shows up in our inventory often enough to talk about here.
If you can store it in a 55-gallon HDPE drum, you can almost certainly store it in an HDPE IBC. If the drum has to be steel or stainless, the IBC does too.