The last time Amazon was worth less than $20 billion was back in March of 2007 [1]. The month prior, they announced results for FYE 2016 [2]. That year, Amazon had net sales of $10.7 billion on which they made a profit of $190 million (page 47). Amazon's operations, meanwhile, produced over $700 million of cash from operations (page 46).
Snap shows $150 million of Q1 2017 revenues. They managed to turn that into a $2.2 billion loss [3]. Next to that, the $150 million of cash their operations lost looks like chump change. (Snap incurred a $2 billion one-time non-cash expense in Q1, so the revenue and cash-from-operations numbers are better for comparison purposes.)
Keep in mind, too, that $1 in March 2007 bought as much as $1.19 bought in March earlier this year [4].
[1] http://www.macrotrends.net/stocks/charts/AMZN/market-cap/ama...
[2] https://www.sec.gov/Archives/edgar/data/1018724/000119312507...
[3] https://www.google.com/finance?q=NYSE%3ASNAP&fstype=ii&ei=f_...
To be fair, a big chunk of that loss was due to many years worth of equity-based compensation (stock options) all booked at once.
Snapchat's total revenue for 2016 was $405M, with net loss of $514M.
The two are not even remotely comparable in terms of financial soundness.