Character space vs storage space

 Storage space — how many distinct bit patterns a fixed amount of memory can hold:

2^bits

A byte = 2⁸ = 256 patterns (0–255). A 5-byte field = 2⁴⁰ ≈ 1.1 trillion patterns. This depends only on the memory, not on what you store.

Character space — how many distinct strings a format can produce:

L^n        L = alphabet size, n = characters

5 chars from a 34-symbol alphabet = 34⁵ = 45,435,424 strings. This depends only on the format, not on the memory.

They're equal only when the alphabet is a power of 2

Format	L	n	Character space	Storage space (1 byte/char)	Fraction used
binary	2	8	256 = 2⁸	2⁸ = 256	1 (no waste)
hex	16	5	16⁵ = 2²⁰	2⁴⁰	1/1,048,576
base-64	64	5	64⁵ = 2³⁰	2⁴⁰	1/1,024
decimal	10	5	10⁵ ≈ 2¹⁶.⁶	2⁴⁰	~1/11,000,000
base-34 (SN)	34	5	34⁵ ≈ 2²⁵.⁴	2⁴⁰	1/24,200

character space intheory is 36 0123456789abcde..z

Theoretically available alphanumerics

36 (0-9, A-Z)