Con palo and sin palo
With stem and without. Stem dilutes the leaf and softens the bitterness, so con palo is milder and lasts longer through refills; sin palo is stronger and harsher and goes flat sooner. Argentine drinkers are broadly split and Uruguayan practice leans strongly to sin palo.
How much powder
Every cut contains some pulverised leaf, and the proportion varies enormously by brand. More powder means a stronger first refill, a cloudier drink and a bombilla that clogs. This is the variable most new drinkers notice and cannot name.
Aged, unaged and smoked
Argentine mate is typically aged for up to a year, which rounds it. Brazilian chimarrão is usually unaged and much greener. Traditional drying over wood fire leaves a smoky note that industrial drying does not, and neither method is stated on most packets.
What to buy first
A con palo Argentine mate is the most forgiving starting point, and moving to sin palo later is a step you can take deliberately. Starting on an unaged sin palo is how most people conclude mate is not for them.