How can we tell whether dark energy is the same as the cosmological constant?

Question: How can we tell whether dark energy is the same as the cosmological constant?
- Keywords:
  cosmological constant,
  dark energy,
  energy
Asked by anon-214678 to Helen, Farah, Dave, Cheryl, Bastian, Alun on 12 Jun 2019.
- Dave Underhill answered on 12 Jun 2019:
  
  we cant – that is one belief though, and establishing the facts around dark energy remains an important job for physicists – essentially what you are asking about is anti-gravity, but we haven’t even worked out gravity yet 🙂 – hopefully, Howard will show up again and explain it better than me!!
- Cheryl Williams answered on 12 Jun 2019:
  
  Not my field of science, sorry 🙂

Question: How can we tell whether dark energy is the same as the cosmological constant?