The terms “stress” and “anxiety” are used moreorless interchangeably – they both reflect symptoms generated via the hypothalamic-pituitary-adrenal (HPA) Axis neurobiologically speaking.
Just for interest’s sake, I’ve found a couple of NHS definitions of stress and anxiety:
“Stress is the feeling of being under too much mental or emotional pressure. Pressure turns into stress when you feel unable to cope. ... Stress causes a surge of hormones in your body. These stress hormones are released to enable you to deal with pressures or threats – the so-called "fight or flight" response.” Ref: https://www.nhsinform.scot/healthy-living/mental-wellbeing/stress/struggling-with-stress
“Anxiety is a feeling of unease, such as worry or fear, that can be mild or severe. Everyone has feelings of anxiety at some point in their life – for example, you may feel worried and anxious about sitting an exam or having a medical test or job interview.” Ref: https://www.nhs.uk/conditions/generalised-anxiety-disorder/
There are many more, even some of which directly contradict one another!
To understand stress and/or anxiety, or it's link with tinnitus, it isn’t important what word we use to describe it – anxiety or stress. Both have the physiological symptoms impact of the HPA Axis.
If you are interested in learning a little more in depth about the Neurochemistry involved in stress, there is an excerpt from The Psychotherapist’s Essential Guide to the Brain by Matthew Dahlitz (2017) available by clicking on the link here