I’d say that, given the fact einsum and matmul operates differently, the error is small enough to be considered as the same.
  

      en.wikipedia.org
  

  
    

Floating-point arithmetic | IEEE 754: floating point in modern computers 1

The IEEE standardized the computer representation for binary floating-point numbers in IEEE 754 (a.k.a. IEC 60559) in 1985. This first standard is followed by almost all modern machines. It was revised in 2008. IBM mainframes support IBM's own hexadecimal floating point format and IEEE 754-2008 decimal floating point in addition to the IEEE 754 binary format. The Cray T90 series had an IEEE version, but the SV1 still uses Cray floating-point format.[citation needed]
 The standard provides for man...