Comparisons
The pairs people mix up most often — batteries and cables — compared on the specifications that decide it, and on whether the swap actually works.
Batteries — cell against cell
SR44 for anything precise, LR44 for anything cheap
CR2032 lasts longer; CR2025 fits tighter holders
Same voltage, entirely different size
CR2032 unless the holder is genuinely too shallow
CR2025 where it fits, CR2016 only where it must
CR2450 for runtime, CR2430 where the holder is shallow
Not interchangeable — the CR2450 is a size class up
No — near-identical thickness, wrong diameter
Not interchangeable — different size class entirely
357 for watches and meters, LR44 for everything cheap
The same cell — SR44 is the standard code, 357 the retail number
The same cell — AG13 is the generic code for an LR44
The same cell — A76 is Energizer's code for the LR44
Same size and chemistry — originally high-drain against low-drain
Same voltage, about three times the runtime
Same 1.5 V, roughly six times the runtime
D for double the runtime, C where a D will not fit
Not interchangeable — the AAAA is a quarter of the cell
One letter apart in the name, about half the cell
Same shape, more than double the voltage — never swap them
AAA-shaped, 3.6 V — not a substitute
Same slot, different voltage — check the device is rated for both
21700 for capacity, 18650 where the tube is already cut for it
26650 for capacity, but far fewer devices take one
Similar capacity, different shape — fit decides it
Same chemistry, entirely different size class
Different size, different voltage, different job
Many torches take either — two CR123A stack to an 18650's length
The same cell — CR123A is the current designation
Both 3 V lithium, but the CR2 is much the smaller cell
Same 12 V and nearly the same length — the A23 is the fatter, longer-lasting one
Batteries — chemistries, formats and codes
The wider questions behind the codes — what the chemistries do differently, and how the naming actually works.
Chemistry
Lithium for cold, weight and high drain; alkaline for everything else
NiMH for anything you replace often, alkaline for anything you forget about
Switch anything you replace more than twice a year
Lithium for standby and extremes, NiMH for anything used often
Different voltages for different jobs — rarely a real choice
NiMH, unless you specifically need what NiCd does
LiFePO4 for longevity and safety, standard lithium-ion for energy per kilo
The same chemistry in a different package
AGM is lead-acid — a sealed version of it
AGM for current, gel for slow deep cycling
Lithium costs more up front and less per year
Formats & codes
Mostly the same words — where it matters, coin means the thin 3 V ones
Silver oxide for precision, alkaline for price
Not alternatives — different voltages for different jobs
L is alkaline, S is silver oxide — the number after is the size
CR for everyday use, BR for heat and long-term stability
One size, two chemistries — the 357 and 303 are the same cell
Cables
Video, audio return, USB and Ethernet — what each standard actually does, and where the names mislead.
Video & display
HDMI for televisions and consoles, DisplayPort for PC monitors
2.1 for 4K120 and 8K — but check what a “2.1” device actually supports
1.4 for high refresh 4K and HDR
HDMI, unless the hardware only offers DVI
HDMI — VGA is analogue and long obsolete
Audio return
USB & Thunderbolt
Not comparable — one is a speed, the other is a plug shape
3.0 is roughly ten times faster and worth it for storage
USB-C is the replacement — A survives on older hardware
Thunderbolt uses the USB-C plug — it is a capability, not a shape
Same top speed — 4 makes the optional parts compulsory
USB-C — Apple has moved to it and Lightning is winding down
USB-C in every respect — micro USB is legacy
Both obsolete — micro is the later and thinner of the two