Are HP toner cartridges 88a and 88x universal?

Not universal.

These two types of toner cartridges have different external structures, so they are not universal. Inappropriate ones will not be put into the printer.

The difference between using HP original toner cartridges and non-original toner cartridges: there are many patents on original consumables, and the quality is guaranteed. Use non-original consumables, including used original consumables, and add powder again. The sealing performance of these consumables is worse than that of HP original consumables, so powder leakage often occurs. Once the toner in the toner box leaks, the conductive toner will cause the printer to short circuit, or even burn the printer, causing huge losses.