Comparisons
Brother PT-320 vs PT-340: keyboard and tape choices
The Brother PT-320 and PT-340 are siblings, not two names for the same keypad. Both are discontinued handheld machines built around a physical QWERTY keyboard, a 15-character one-line display, two printed lines, manual cutting and six AA cells or an optional AD-30. The PT-340 is the more decorated of the two; the PT-320 is the simpler choice if those extra formats are not part of the job.
What the PT-340 adds
Brother's PT-340 brochure lists three regular fonts plus five title fonts, eight character sizes and styles, 128 symbols and ten framing choices. The shared guide gives the PT-340 nine symbol groups, compared with four for the PT-320. It also describes repeat printing and automatic numbering; the brochure says repeat printing can run up to nine copies. The PT-320 has its own useful format choices, but not the PT-340's larger symbol and title-font set. If you mostly type shelf names, dates or file labels, those extras may not change the outcome. If a few labels need a distinctive title treatment or a particular symbol, they can be a genuine convenience.
Do not collapse the tape evidence
The older PT-320/340 guide specifies original Brother TZ cassettes in 6, 9, 12 and 18 mm and instructs the owner to use TZ tape. Brother's current U.S. PT-320 and PT-340 product records separately list TZe widths from 3.5 to 12 mm, and its 9 mm TZe521CS supply listing names both models. The old TZ guide and the current TZe record therefore support two bounded plans; 18 mm in the old guide is not 18 mm TZe. Check the cassette family and exact width against the machine and current Brother listing before buying stock. Both models use a manual cutter lever, not a documented automatic full-cut cycle. Neither the one-line screen nor the ability to print two lines proves a particular numeric print height.
Choosing between a working unit and a current workflow
Keep the PT-320 in view when a known working example and a short, straightforward text job are enough. Prefer the PT-340 if you will actually use its larger symbol set, title fonts or framing options. Both need room for a roughly 7-inch-wide, nearly 8-inch-deep body and a little hand space at the tape exit. The PT-340's original brochure lists a case, six AA batteries, a black-on-clear starter tape, separator and lettering stick; the optional adapter is not presented as a standard inclusion. A used machine's present contents can differ, so check the actual listing and physical condition.
If the goal is a new standard-TZe purchase, compare either earlier unit with the current PT-D410 instead of treating the older manual as a new-media promise. Read the individual PT-320 review and PT-340 review for the operating-plan details. Choose the PT-340 for its added on-device design options, not on the assumption that it offers an app, a computer connection, or automatic cutting.