LTC has a lot fewer transactions per block. Mostly none besides the reward, actually.
There may be some truth to it, the average # of LTC transactions is somewhere 4~5 per block,
http://explorer.litecoin.net/chain/Litecoinan equivalent of 20 transactions per BTC block. OTOH average BTC block has 130 transactions currently.
So, 6~7 times more data and only 2~3 times slower, BTC network doesn't look that bad after all.