Taste the Difference
Thai food is rather vogue nowadays, with even major food chains touting "Thai-style" dishes - Noodles & Co. comes to mind, whose pad thai is actually quite good. This was hardly the case about ten years ago when, even though Thai restaurants existed in some number, Thai cuisine was not yet widely-recognized. These days most people I encounter have at least sampled Thai food; most have favorite dishes they can order by name.
However, with increasing popularity comes the need to cater to a broader audience, which leads to certain concessions in taste and use of ingredients. That, combined with the abundance of pan-Asian restaurants, fusion dishes, and packaged products masquerading as "authentically" Thai, has somewhat blurred Thai cuisine's "identity" in popular culture - a distinction that was perhaps not altogether vivid to begin with.
I bring this up because today my lunch-partner commented that Thai food is not much different from Chinese. Initially I was taken aback (in my typically nationalistic manner), but after my senses returned I couldn't blame him for the misconception.
The most popular and widely-recognized Thai dishes in the US - noodles and stirfries - confess a clear Chinese influence. The reasons for this are partly historical: in urban areas like Bangkok, people of Chinese-descent form a large portion of the population. Secondly, and more practically, noodles and stirfries are quickly prepared, appeal to tongues already familiar with orange chicken and chow mein, and package nicely in to-go boxes.
If you go outside the cities, where the population is more ethnically Thai (or our close relatives, the Lao), you'll find what might be more truthfully called "authentic" Thai cuisine: dishes like green papaya salad or minced meat tossed with lime juice and fish sauce. It's these dishes that have yet to win over the average American palette. And so, except for the aficionado, the food at local Thai restaurants may seem suspiciously Chinese.
If we define a region's cuisine as the way local and traditional ingredients are prepared, presented, and to some extent eaten, Thai cuisine is easily distinguished from Chinese. For example, Thai cooks use fish sauce over soy, and hoisin is virtually unknown in Thai kitchens. Instead, herbs like lemongrass, kaffir lime leaf, and galangal are more commonly found in Thai cooking. Finally, on a topical note, chopsticks are used in Thailand expressly for noodles and other Chinese-influenced dishes. Otherwise, tables are set with spoons and forks.
(I realize that using umbrella terms like "Chinese" is troublesome; of course I don't mean to say that I can make decisive generalizations about China's profusion of cultures and ethnic groups. My judgments are based on the "common fare" typical of Chinese restaurants and buffets in the US.)
However, my purpose here isn't really to expound on the intricacies of Thai cuisine. Instead I'll say that, ultimately, if Thai cuisine is confused with Chinese or other Asian culinary traditions in the American popular appetite, the fault lies squarely with the owners and managers of Thai restaurants, who are the primary transmitters of Thai cuisine into the US. If they do not strive to uphold traditional standards and make instead a sort of Americanized concession ("McThai Food"), Thai cuisine will inevitably lose the unique flavors that make it a joy to those of us who appreciate it most.
Finally, here's an excellent primer to Thai cuisine, categorized by region, by the Tourism Authority: