How do Bitcoin and Litecoin compare in scalability? Bitcoin and Litecoin are very similar, however they differ in the hash algorithm, the block interval and reward schedule. How do these characteristics impact the scalability in terms of e.g. transaction capacity, IBD, CONOP, light weight node requirements, and block verification times?
Litecoin is using largely the same consensus rules as Bitcoin with a few exceptions:


its blockchain derives from a distinct Genesis block
it targets a block interval of 2.5 minutes (10 minutes on Bitcoin)
halvings happen every 840,000 blocks (210,000 on Bitcoin)
block hashes are calculated with Scrypt instead of SHA-256d


Since the more costly Scrypt hashing algorithm needs to be only performed once per block in block validation, the effect on the IBD should be negligible compared to other steps in the validation. H/T @Nate Eldredge.

Since Litecoin has also activated segwit, its transaction capacity is roughly four times that of Bitcoin. Theoretically, this could cause Litecoin's blockchain footprint to increase at up to four times Bitcoin's rate, presumably increasing the IBD at least at the same rate. I surmise that the IBD might increase superlinearly to the blockchain footprint as it would likely correspond to a higher UTXO count as well. In practice, Litecoin is only using a fraction of its blockspace and should have a significantly faster IBD.