They are not co-equal in the sense of equivalence. Because they have different roles and responsibilities with some minor overlap.

Congress cannot make administrative law or enforce law.

The Executive cannot appropriate money.

The Judiciary cannot enforce law or make laws.

For example: courts can issue contempt orders against the Executive branch (and many have) but the Executive branch can ignore them (as many have); Congress can pass as many laws as it wants, but unless the executive branch enforces those laws they mean little; the Executive can refuse to appoint/nominate Judges and Justices, nothing Congress or the Judiciary can do about that; and so on.