I would expect that you could go to almost any electrode manufacturer's website and see the difference between the different electrodes.
The -HX indicates the diffusible hydrogen, E7018: 16 ml/100g of weld deposit, E7018-H8: 8 ml/100g, E7018-H4: 4 ml/100g
The suffix letters indicate the alloy additions contained in the flux covering. A - molybdenum, B - chrome moly, C - nickel. The numbers that follow the suffix letter differentiate the percentages of alloy added, but not as a direct percentage. That is to say, E8018-C1 is not 1% nickel, nor is E8018-C2 actually 2% nickel. Instead, C1 is 2.5% nickel, C2 is 3% nickel, and C3 is 1% nickel. Check my percentages, they may be wrong, but you get the idea.
Check the websites for Lincoln and ESAB.
Best regards - Al
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