New Zealand's vibrant culinary landscape reflects the country’s rich cultural tapestry and abundant natural resources. When considering delving into the food retail business here, it's vital to understand the various avenues available, their profitability, ease of establishment, and potential challenges. Here's a comprehensive overview for the aspiring entrepreneur:

1. Types of Small and Medium-Sized Food Retail Ventures:

Bakeries and Patisseries: Specialising in bread, pastries, or both. They are popular and can be started with limited resources.
Speciality Gourmet Shops: Focusing on particular items like cheeses, chocolates, organic foods, or international products.
Butchers: Offering meat, poultry, and sometimes seafood.
Green Grocers: Specialising in fruits, vegetables, and other farm-fresh products.
Cafés and Coffee Shops: Where the primary focus lies in serving hot beverages, baked goods, and light meals.
Food Trucks: Mobile restaurants, often specialising in a single type of cuisine or dish.
Online Food Retail: Catering to a tech-savvy audience that prefers ordering online.

2. Profitability and Simplicity:

Most Profitable: Cafés and coffee shops, given New Zealand’s café culture, often see high footfalls. Speciality gourmet shops catering to niche markets can also yield substantial margins.
Easiest to Establish: Food trucks and online food retail are relatively easy to set up, with the latter requiring minimal physical infrastructure.
Solo Ventures: Bakeries, especially if they focus on a limited range of products, or online food retail, can be managed single-handedly, at least initially.

3. Challenges:

Regulatory Hurdles: New Zealand has stringent food safety and hygiene regulations. It's crucial to be well-versed with them before setting up any food-related venture.
Stiff Competition: The food retail sector is crowded. Differentiating your venture and carving a niche becomes essential.
Supply Chain Complexities: Ensuring a consistent supply of fresh ingredients can be challenging, especially for businesses reliant on seasonal produce.

4. Advantages Over Other Businesses:

Evergreen Demand: Food is a basic necessity. With the right approach, there's always a market for quality food products.
Diverse Opportunities: From traditional brick-and-mortar establishments to online ventures, there’s a broad spectrum of opportunities.
Personal Satisfaction: There's a unique joy in serving quality food products to customers and receiving their appreciation.

5. Key Takeaways:

Research Thoroughly: Before diving in, understand the market, customer preferences, and current trends.
Start Small: Especially if you're a first-time entrepreneur. Begin with a limited range of products and expand as you grasp the market.
Embrace Technology: Leveraging social media and having an online presence can significantly boost your venture.

In conclusion, while the food retail business in New Zealand presents immense potential, it's essential to approach it with a mix of passion, prudence, and patience. Whether you’re serving a handcrafted pie, a cup of artisanal coffee, or an exotic cheese, it’s about creating memorable experiences for the consumer.