I'm making my own monster list and I see in the back of Volo's under the Environment list it shows “apprentice” under “urban” with a CR of 1/8. In the CR list it only shows “apprentice wizard” with a CR of 1/4. Am I missing something? Where is the 1/8 CR apprentice?
You aren't missing anything. You can't find the CR 1/8 Apprentice Wizard because it's a typo.
The Apprentice Wizard in that table has been incorrectly assigned to the CR 1/8 line. As you've noted, if you check the "Stat Blocks by Challenge Rating" table the Apprentice Wizard is correctly listed as a CR 1/4 creature.
For further confirmation of this, the D&D Monster Lists PDF (as published in November 2017) has the Apprentice Wizard correctly listed as a CR 1/4 creature, attributed to Volo's Guide to Monsters. It also does not have a CR 1/8 version listed anywhere.
5\$\begingroup\$ This is further supported by this dnd beyond search if you want to include it to show there is no other "apprentice" creature \$\endgroup\$– SdjzMar 14, 2019 at 14:24
\$\begingroup\$ Yes I understand that is probably the issue. If it is then there are two typos. the environment shows apprentice and not apprentice wizard. \$\endgroup\$ Mar 14, 2019 at 14:28
5\$\begingroup\$ Also of note is the fact that "apprentice wizard" would be otherwise not mentioned in any environment \$\endgroup\$– SdjzMar 14, 2019 at 14:31
\$\begingroup\$ @Sdjz I'll note the second point when I get home. The search link though is both not future proof and requires users to go offsite, which I'd prefer to avoid. \$\endgroup\$– illustroMar 14, 2019 at 15:23
2\$\begingroup\$ I mean, it does stand to reason that a generic apprentice (like, apprentice cobbler? apprentice cheesemaker? whatever!) would be a lower CR than an apprentice wizard. \$\endgroup\$– mattdmMar 14, 2019 at 19:05