Jelly, 5 bytes

ÆfI¬S

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Verify all testcases.

Port of Luis Mendo's answer in MATL.

ÆfI¬S

Æf     Implicit input. Obtain prime factors, sorted and with repetitions
  I    Consecutive differences
   ¬   Logical negate: zeros become 1, nonzeros become 0
    S  Sum. Implicit display

Jelly, 5 bytes

ÆfI¬S

Try it online!

Verify all testcases.

Port of Luis Mendo's answer in MATL.

ÆfI¬S

Æf     Implicit input. Obtain prime factors, sorted and with repetitions
  I    Consecutive differences
   ¬   Logical negate: zeros become 1, nonzeros become 0
    S  Sum. Implicit display

Jelly, 5 bytes

ÆfI¬S

Try it online!

Port of Luis Mendo's answer in MATL.

ÆfI¬S

Æf     Implicit input. Obtain prime factors, sorted and with repetitions
  I    Consecutive differences
   ¬   Logical negate: zeros become 1, nonzeros become 0
    S  Sum. Implicit display

Jelly, 5 bytes

ÆfI¬S

Try it online!

Verify all testcases.

Port of Luis Mendo's answer in MATL.

ÆfI¬S

Æf     Implicit input. Obtain prime factors, sorted and with repetitions
  I    Consecutive differences
   ¬   Logical negate: zeros become 1, nonzeros become 0
    S  Sum. Implicit display

Jelly, 7 bytes

ÆFµSṪ_L

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ÆFµSṪ_L

ÆF        Compute prime factorization as [prime, exponent] pairs.
  µ       Start a new monadic chain whose argument is above.
   S      Vectorized sum (sum of primes, sum of exponents).
    Ṫ     Last element (sum of exponents).
     _    Above minus below.
      L   Length (of the [prime, exponent] pairs).

Alternative

ÆfµQLạL

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ÆfµQLạL

Æf        Compute the array of primes whose product is z.
  µ       Start a new monadic chain whose argument is above.
   Q      Unique elements sorted by first appearance.
    L     Length.
     ạ    Above absolute_difference below.
      L   Length (of the [prime, exponent] pairs).

Jelly, 5 bytes

ÆfI¬S

Try it online!

Port of Luis Mendo's answer in MATL.

ÆfI¬S

Æf     Implicit input. Obtain prime factors, sorted and with repetitions
  I    Consecutive differences
   ¬   Logical negate: zeros become 1, nonzeros become 0
    S  Sum. Implicit display