Anxiety is the projection or anticipation of misfortune or danger in the future which is accompanied by a painful sense of internal tension and may have physical manifestations as well. Stress is that natural energy necessary to tolerate and/or negotiate one's
obligations or expectations.
Why is this even something to consider if the symptoms are the same? We could just treat the symptoms any number of ways:
medications, substances, denial, impulsive behaviors, etc. that may give temporary relief, but may also increase problems in the future.
Since the definition of anxiety offered above has to do with the mindset of a person, it is most fully addressed by changing the way one thinks. We may overestimate the downside of possible events, we may overestimate the likelihood of misfortune, we may think particular outcomes or events would be too malevolent for us to "stand" or that if certain things happen we would be unable to survive or overcome them (unable to ever experience happiness); but the truth is we can "stand" much more than we think and as long as we have life, breath and awareness we are able to make choices in pursuit of happiness. The resultant anxiety then sets in motion a physiological response that prepares us to "fight or escape" the danger, when there is nothing to fight or escape. That
physiological state is meant to assist us in emergency situations only and if it is activated continuously by the above thinking patterns, then this natural protective response begins to take a negative toll on us. So instead, we would do well to make reasonable decisions about risks, but face the fear (exposure) of those risks in favor of the benefits. We cannot avoid risk. All relationships inherently involve risk.
Stress is unavoidable also. Most of us in this culture are extremely busy and will often over obligate ourselves or allow expectations (whether from others or ourselves) to overwhelm us. If a person allows themselves to continually strive without taking time to allow themselves to recover, their mind, body and spirit will eventually begin to shut down with a variety of symptoms: lack of motivation, stomach problems, physical pain, anger, unwise risk taking, impulsive behaviors, increased substance use, etc. An
easy example to demonstrate is someone going to the gym. If that person "stresses" their body in exercise continuously, they will eventually give out and their body will not allow them to go on; but if they stress their body in exercise for a period of time and then rest (allowing recovery time) they become stronger and increase their resilience. With that same example, if a person in the gym lifts more weight than their body is capable of, they may injure themselves. Lesson: to manage stress, reduce obligations, prioritize and give yourself some recovery time (meditation, recreation, hobbies, spend some time with family/ friends, adopt a healthy lifestyle, connect spiritually, etc.).
So (1) consider risks of life as objectively as possible, face the risks of life without overestimating the negative consequences, and balance the potential good of any risk and (2) manage your obligations and take time to recover